diff --git a/nml/actions/action0.py b/nml/actions/action0.py
index be0249100..ca576c5c1 100644
--- a/nml/actions/action0.py
+++ b/nml/actions/action0.py
@@ -458,7 +458,7 @@ def get_property_info_list(feature, name):
     if isinstance(name, expression.Identifier):
         prop_name = name.value
         if prop_name not in properties[feature]:
-            raise generic.ScriptError("Unknown property name: " + prop_name, name.pos)
+            raise generic.ScriptError(f"Unknown property name: {prop_name}", name.pos)
         prop_info_list = properties[feature][prop_name]
         if not isinstance(prop_info_list, list):
             prop_info_list = [prop_info_list]
@@ -470,7 +470,7 @@ def get_property_info_list(feature, name):
             if len(prop_info_list) == 1 and "num" in prop_info_list[0] and prop_info_list[0]["num"] == name.value:
                 break
         else:
-            raise generic.ScriptError("Unknown property number: " + str(name), name.pos)
+            raise generic.ScriptError(f"Unknown property number: {str(name)}", name.pos)
     else:
         raise AssertionError()
 
@@ -635,7 +635,7 @@ def apply_threshold(value):
             elif isinstance(value, expression.String):
                 if "string" not in prop_info:
                     raise generic.ScriptError(
-                        "String used as value for non-string property: " + str(prop_info["num"]), value.pos
+                        f"String used as value for non-string property: {str(prop_info["num"])}", value.pos
                     )
                 string_range = apply_threshold(prop_info["string"])
                 stringid, string_actions = action4.get_string_action4s(feature, string_range, value, id)
diff --git a/nml/actions/action0properties.py b/nml/actions/action0properties.py
index e7aa8b7c9..b178f277c 100644
--- a/nml/actions/action0properties.py
+++ b/nml/actions/action0properties.py
@@ -237,7 +237,7 @@ def animation_info(value, loop_bit=8, max_frame=253):
         raise generic.ScriptError("First field of the animation_info array must be either 0 or 1", value.values[0].pos)
     if frames < 1 or frames > max_frame:
         raise generic.ScriptError(
-            "Second field of the animation_info array must be between 1 and " + str(max_frame), value.values[1].pos
+            f"Second field of the animation_info array must be between 1 and {str(max_frame)}", value.values[1].pos
         )
 
     return ConstantNumeric((looping << loop_bit) + frames - 1)
@@ -1526,7 +1526,7 @@ def get_size(self):
 
 def label_list(value, prop_num, description):
     if not isinstance(value, Array):
-        raise generic.ScriptError(description + " list must be an array of literal strings", value.pos)
+        raise generic.ScriptError(f"{description} list must be an array of literal strings", value.pos)
     return [LabelListProp(prop_num, value.values)]
 
 
@@ -1642,7 +1642,7 @@ def write(self, file):
         for item in self.items:
             val = item.reduce_constant().value
             if val > 0xFF or val < 0:
-                raise generic.ScriptError(self.description + " items must be bytes", self.pos)
+                raise generic.ScriptError(f"{self.description} items must be bytes", self.pos)
             file.print_byte(val)
         file.newline()
 
@@ -1652,7 +1652,7 @@ def get_size(self):
 
 def byte_sequence_list(value, prop_num, description, expected_count):
     if not isinstance(value, Array) or len(value.values) != expected_count:
-        raise generic.ScriptError(description + " must be an array of " + str(expected_count) + " bytes", value.pos)
+        raise generic.ScriptError(f"{description} must be an array of {str(expected_count)} bytes", value.pos)
     return [ByteSequenceProp(prop_num, value.values, description, value.pos)]
 
 
diff --git a/nml/actions/action2layout.py b/nml/actions/action2layout.py
index 1371e6340..656d1e008 100644
--- a/nml/actions/action2layout.py
+++ b/nml/actions/action2layout.py
@@ -257,7 +257,7 @@ def _validate_offset(self, offset, spriteset, pos):
                     pos,
                 )
         else:
-            raise generic.ScriptError("Expected 0 or 1 parameter, got " + str(len(offset)), pos)
+            raise generic.ScriptError(f"Expected 0 or 1 parameter, got {str(len(offset))}", pos)
         return offset
 
     def resolve_spritegroup_ref(self, sg_ref):
@@ -355,10 +355,10 @@ def _validate_always_draw(self, name, value):
 
     def _validate_bounding_box(self, name, value):
         if self.type == Action2LayoutSpriteType.GROUND:
-            raise generic.ScriptError(name + " can not be set for ground sprites", value.pos)
+            raise generic.ScriptError(f"{name} can not be set for ground sprites", value.pos)
         elif self.type == Action2LayoutSpriteType.CHILD:
             if name not in ("xoffset", "yoffset"):
-                raise generic.ScriptError(name + " can not be set for child sprites", value.pos)
+                raise generic.ScriptError(f"{name} can not be set for child sprites", value.pos)
             if isinstance(value, expression.ConstantNumeric):
                 generic.check_range(value.value, 0, 255, name, value.pos)
                 return value
diff --git a/nml/actions/action5.py b/nml/actions/action5.py
index 4c16955d1..3907148d3 100644
--- a/nml/actions/action5.py
+++ b/nml/actions/action5.py
@@ -94,7 +94,7 @@ def parse_action5(replaces):
     num_sprites = len(real_sprite_list)
 
     if replaces.type.value not in action5_table:
-        raise generic.ScriptError(replaces.type.value + " is not a valid sprite replacement type", replaces.type.pos)
+        raise generic.ScriptError(f"{replaces.type.value} is not a valid sprite replacement type", replaces.type.pos)
     type_id, num_required, block_type = action5_table[replaces.type.value]
     offset = None
 
diff --git a/nml/actions/real_sprite.py b/nml/actions/real_sprite.py
index 5cb016965..45af596b9 100644
--- a/nml/actions/real_sprite.py
+++ b/nml/actions/real_sprite.py
@@ -422,7 +422,7 @@ def debug_print(self, indentation):
     def get_labels(self):
         # Load labels from the template definition
         if self.name.value not in sprite_template_map:
-            raise generic.ScriptError("Encountered unknown template identifier: " + self.name.value, self.name.pos)
+            raise generic.ScriptError(f"Encountered unknown template identifier: {self.name.value}", self.name.pos)
         labels, offset = sprite_template_map[self.name.value].get_labels()
         # Add (possibly) label applied to ourselves
         if self.label is not None:
@@ -435,14 +435,13 @@ def get_labels(self):
 
     def expand(self, default_file, default_mask_file, poslist, parameters):
         if self.name.value not in sprite_template_map:
-            raise generic.ScriptError("Encountered unknown template identifier: " + self.name.value, self.name.pos)
+            raise generic.ScriptError(f"Encountered unknown template identifier: {self.name.value}", self.name.pos)
         template = sprite_template_map[self.name.value]
         if len(self.param_list) != len(template.param_list):
             raise generic.ScriptError(
-                "Incorrect number of template arguments. Expected "
-                + str(len(template.param_list))
-                + ", got "
-                + str(len(self.param_list)),
+                "Incorrect number of template arguments. Expected {}, got {}".format(
+                    str(len(template.param_list)), str(len(self.param_list))
+                ),
                 self.pos,
             )
         param_dict = {}
diff --git a/nml/ast/alt_sprites.py b/nml/ast/alt_sprites.py
index a07d17c17..b52ac5f39 100644
--- a/nml/ast/alt_sprites.py
+++ b/nml/ast/alt_sprites.py
@@ -47,7 +47,7 @@ def __init__(self, param_list, sprite_list, pos):
         base_statement.BaseStatement.__init__(self, "alt_sprites-block", pos)
         if not (3 <= len(param_list) <= 5):
             raise generic.ScriptError(
-                "alternative_sprites-block requires 3 or 4 parameters, encountered " + str(len(param_list)), pos
+                f"alternative_sprites-block requires 3 or 4 parameters, encountered f{str(len(param_list))}", pos
             )
 
         self.name = param_list[0]
diff --git a/nml/ast/error.py b/nml/ast/error.py
index 42cb86880..2490490ee 100644
--- a/nml/ast/error.py
+++ b/nml/ast/error.py
@@ -46,7 +46,7 @@ def __init__(self, param_list, pos):
         base_statement.BaseStatement.__init__(self, "error()", pos)
         if not 2 <= len(param_list) <= 5:
             raise generic.ScriptError(
-                "'error' expects between 2 and 5 parameters, got " + str(len(param_list)), self.pos
+                f"'error' expects between 2 and 5 parameters, got {str(len(param_list))}", self.pos
             )
         self.severity = param_list[0]
         self.msg = param_list[1]
diff --git a/nml/ast/font.py b/nml/ast/font.py
index 12a3b642c..e33248848 100644
--- a/nml/ast/font.py
+++ b/nml/ast/font.py
@@ -41,7 +41,7 @@ def __init__(self, param_list, sprite_list, name, pos):
         sprite_container.SpriteContainer.__init__(self, "font_glyph-block", name)
         if not (2 <= len(param_list) <= 3):
             raise generic.ScriptError(
-                "font_glyph-block requires 2 or 3 parameters, encountered " + str(len(param_list)), pos
+                f"font_glyph-block requires 2 or 3 parameters, encountered {str(len(param_list))}", pos
             )
         self.font_size = param_list[0]
         self.base_char = param_list[1]
diff --git a/nml/ast/grf.py b/nml/ast/grf.py
index 3440b1fd4..0acb9fca8 100644
--- a/nml/ast/grf.py
+++ b/nml/ast/grf.py
@@ -107,7 +107,7 @@ def __init__(self, alist, pos):
             elif assignment.name.value == "min_compatible_version":
                 self.min_compatible_version = assignment.value
             else:
-                raise generic.ScriptError("Unknown item in GRF-block: " + str(assignment.name), assignment.name.pos)
+                raise generic.ScriptError(f"Unknown item in GRF-block: {str(assignment.name)}", assignment.name.pos)
 
     def register_names(self):
         generic.OnlyOnce.enforce(self, "GRF-block")
@@ -301,7 +301,7 @@ def set_property(self, name, value):
             if self.type == "bool" and self.def_val.value != 0 and self.def_val.value != 1:
                 raise generic.ScriptError("setting-def_value must be either 0 or 1 for 'bool' settings", value.pos)
         else:
-            raise generic.ScriptError("Unknown setting-property " + name, value.pos)
+            raise generic.ScriptError(f"Unknown setting-property {name}", value.pos)
 
 
 class ParameterDescription:
diff --git a/nml/ast/replace.py b/nml/ast/replace.py
index 71c723f4b..ac9451f38 100644
--- a/nml/ast/replace.py
+++ b/nml/ast/replace.py
@@ -39,7 +39,7 @@ def __init__(self, param_list, sprite_list, name, pos):
 
         num_params = len(param_list)
         if not (1 <= num_params <= 2):
-            raise generic.ScriptError("replace-block requires 1 or 2 parameters, encountered " + str(num_params), pos)
+            raise generic.ScriptError(f"replace-block requires 1 or 2 parameters, encountered {str(num_params)}", pos)
         self.start_id = param_list[0]
         if num_params >= 2:
             self.image_file = param_list[1].reduce()
@@ -112,7 +112,7 @@ def __init__(self, param_list, sprite_list, name, pos):
         num_params = len(param_list)
         if not (1 <= num_params <= 3):
             raise generic.ScriptError(
-                "replacenew-block requires 1 to 3 parameters, encountered " + str(num_params), pos
+                f"replacenew-block requires 1 to 3 parameters, encountered {str(num_params)}", pos
             )
 
         self.type = param_list[0]
diff --git a/nml/ast/spriteblock.py b/nml/ast/spriteblock.py
index ad106c402..2c0d2a241 100644
--- a/nml/ast/spriteblock.py
+++ b/nml/ast/spriteblock.py
@@ -36,7 +36,7 @@ def pre_process(self):
                     )
                 elif sprite.name.value not in real_sprite.sprite_template_map:
                     raise generic.ScriptError(
-                        "Encountered unknown template identifier: " + sprite.name.value, sprite.pos
+                        f"Encountered unknown template identifier: {sprite.name.value}", sprite.pos
                     )
         # Register template
         if self.name.value not in real_sprite.sprite_template_map:
@@ -88,7 +88,7 @@ class SpriteSet(spriteset_base_class, sprite_container.SpriteContainer):
     def __init__(self, param_list, sprite_list, pos):
         base_statement.BaseStatement.__init__(self, "spriteset", pos, False, False)
         if not (1 <= len(param_list) <= 5):
-            raise generic.ScriptError("Spriteset requires 1 to 5 parameters, encountered " + str(len(param_list)), pos)
+            raise generic.ScriptError(f"Spriteset requires 1 to 5 parameters, encountered {str(len(param_list))}", pos)
         name = param_list[0]
         if not isinstance(name, expression.Identifier):
             raise generic.ScriptError("Spriteset parameter 1 'name' should be an identifier", name.pos)
diff --git a/nml/ast/switch.py b/nml/ast/switch.py
index 0bacd0b5c..9549080b9 100644
--- a/nml/ast/switch.py
+++ b/nml/ast/switch.py
@@ -28,7 +28,7 @@ def __init__(self, param_list, body, pos):
         base_statement.BaseStatement.__init__(self, "switch-block", pos, False, False)
         if len(param_list) < 4:
             raise generic.ScriptError(
-                "Switch-block requires at least 4 parameters, encountered " + str(len(param_list)), pos
+                f"Switch-block requires at least 4 parameters, encountered {str(len(param_list))}", pos
             )
         if not isinstance(param_list[1], expression.Identifier):
             raise generic.ScriptError(
@@ -380,7 +380,7 @@ def pre_process(self):
         self.triggers = self.triggers.reduce_constant(global_constants.const_list)
         if not (0 <= self.triggers.value <= 255):
             raise generic.ScriptError(
-                "random_switch parameter 4 'triggers' out of range 0..255, encountered " + str(self.triggers.value),
+                f"random_switch parameter 4 'triggers' out of range 0..255, encountered {str(self.triggers.value)}",
                 self.triggers.pos,
             )
 
diff --git a/nml/expression/cargo.py b/nml/expression/cargo.py
index 4530609b7..e6259dd1f 100644
--- a/nml/expression/cargo.py
+++ b/nml/expression/cargo.py
@@ -29,7 +29,7 @@ def cargolabel(self):
         for label, number in global_constants.cargo_numbers.items():
             if number == self.cargotype:
                 return label
-        raise AssertionError("Cargo expression with unregistered cargotype at " + str(self.pos))
+        raise AssertionError(f"Cargo expression with unregistered cargotype at {str(self.pos)}")
 
     def debug_print(self, indentation):
         if self.value is None:
diff --git a/nml/expression/functioncall.py b/nml/expression/functioncall.py
index c8a4ec4af..27b318196 100644
--- a/nml/expression/functioncall.py
+++ b/nml/expression/functioncall.py
@@ -244,7 +244,7 @@ def builtin_day_of_year(name, args, pos):
     @return Day of the year, assuming February has 28 days.
     """
     if len(args) != 2:
-        raise generic.ScriptError(name + "() must have a month and a day parameter", pos)
+        raise generic.ScriptError(f"{name}() must have a month and a day parameter", pos)
 
     month = args[0].reduce()
     if not isinstance(month, ConstantNumeric):
@@ -275,21 +275,21 @@ def builtin_storage(name, args, pos):
 @builtin
 def builtin_UCMP(name, args, pos):
     if len(args) != 2:
-        raise generic.ScriptError(name + "() must have exactly two parameters", pos)
+        raise generic.ScriptError(f"{name}() must have exactly two parameters", pos)
     return nmlop.VACT2_UCMP(args[0], args[1], pos)
 
 
 @builtin
 def builtin_CMP(name, args, pos):
     if len(args) != 2:
-        raise generic.ScriptError(name + "() must have exactly two parameters", pos)
+        raise generic.ScriptError(f"{name}() must have exactly two parameters", pos)
     return nmlop.VACT2_CMP(args[0], args[1], pos)
 
 
 @builtin
 def builtin_rotate(name, args, pos):
     if len(args) != 2:
-        raise generic.ScriptError(name + "() must have exactly two parameters", pos)
+        raise generic.ScriptError(f"{name}() must have exactly two parameters", pos)
     return nmlop.ROT_RIGHT(args[0], args[1], pos)
 
 
@@ -306,7 +306,7 @@ def builtin_hasbit(name, args, pos):
     @return C{1} if and only if C{value} has bit C{bit_num} set, C{0} otherwise.
     """
     if len(args) != 2:
-        raise generic.ScriptError(name + "() must have exactly two parameters", pos)
+        raise generic.ScriptError(f"{name}() must have exactly two parameters", pos)
     return nmlop.HASBIT(args[0], args[1], pos)
 
 
@@ -319,7 +319,7 @@ def builtin_getbits(name, args, pos):
             that is (C{value} >> C{first}) & (1 << C{amount} - 1)
     """
     if len(args) != 3:
-        raise generic.ScriptError(name + "() must have exactly three parameters", pos)
+        raise generic.ScriptError(f"{name}() must have exactly three parameters", pos)
 
     # getbits(value, first, amount) = (value >> first) & ((0xFFFFFFFF << amount) ^ 0xFFFFFFFF)
     part1 = nmlop.SHIFTU_RIGHT(args[0], args[1], pos)
@@ -340,19 +340,19 @@ def builtin_version_openttd(name, args, pos):
     @return The version information encoded in a double-word.
     """
     if len(args) < 2:
-        raise generic.ScriptError(name + "() must have at least 2 parameters", pos)
+        raise generic.ScriptError(f"{name}() must have at least 2 parameters", pos)
 
     major = args[0].reduce_constant().value
     minor = args[1].reduce_constant().value
 
     if major >= 12:
         if len(args) != 2:
-            raise generic.ScriptError(name + "() must have at exactly 2 parameters for OpenTTD >= 12.0", pos)
+            raise generic.ScriptError(f"{name}() must have at exactly 2 parameters for OpenTTD >= 12.0", pos)
 
         return ConstantNumeric(((16 + major) << 24) | (minor << 20))
     else:
         if len(args) > 4:
-            raise generic.ScriptError(name + "() must have at most 4 parameters", pos)
+            raise generic.ScriptError(f"{name}() must have at most 4 parameters", pos)
 
         revision = args[2].reduce_constant().value if len(args) >= 3 else 0
         build = args[3].reduce_constant().value if len(args) >= 4 else 0x80000
@@ -374,7 +374,7 @@ def builtin_typelabel_available(name, args, pos):
     }[name]
 
     if len(args) != 1:
-        raise generic.ScriptError(name + "() must have exactly 1 parameter", pos)
+        raise generic.ScriptError(f"{name}() must have exactly 1 parameter", pos)
     label = args[0].reduce()
     return SpecialCheck(op, 0, (0, 1), parse_string_to_dword(label), "{}({})".format(name, label), pos=args[0].pos)
 
@@ -404,7 +404,7 @@ def builtin_grf_status(name, args, pos):
         string = "{}({}, {})".format(name, grfid, mask)
         varsize = 8
     else:
-        raise generic.ScriptError(name + "() must have 1 or 2 parameters", pos)
+        raise generic.ScriptError(f"{name}() must have 1 or 2 parameters", pos)
 
     return SpecialCheck(op, 0x88, results, parse_string_to_dword(grfid), string, varsize, mask, args[0].pos)
 
@@ -421,7 +421,7 @@ def builtin_visual_effect_and_powered(name, args, pos):
     """
     arg_len = 2 if name == "visual_effect" else 3
     if len(args) != arg_len:
-        raise generic.ScriptError(name + "() must have {:d} parameters".format(arg_len), pos)
+        raise generic.ScriptError(f"{name}() must have {arg_len:d} parameters", pos)
     effect = args[0].reduce_constant(global_constants.const_list).value
     offset = nmlop.ADD(args[1], 8).reduce_constant().value
     generic.check_range(offset, 0, 0x0F, "offset in function " + name, pos)
@@ -448,7 +448,7 @@ def builtin_create_effect(name, args, pos):
 
     """
     if len(args) != 4:
-        raise generic.ScriptError(name + "() must have 4 parameters", pos)
+        raise generic.ScriptError(f"{name}() must have 4 parameters", pos)
 
     sprite = args[0].reduce_constant(global_constants.const_list).value
     offset1 = args[1].reduce_constant().value
@@ -466,7 +466,7 @@ def builtin_create_effect(name, args, pos):
 @builtin
 def builtin_str2number(name, args, pos):
     if len(args) != 1:
-        raise generic.ScriptError(name + "() must have 1 parameter", pos)
+        raise generic.ScriptError(f"{name}() must have 1 parameter", pos)
     return ConstantNumeric(parse_string_to_dword(args[0]))
 
 
@@ -491,7 +491,7 @@ def builtin_resolve_typelabel(name, args, pos, table_name=None):
         table_name = "cargo"  # NML syntax uses "cargotable" and "railtypetable"
 
     if len(args) != 1:
-        raise generic.ScriptError(name + "() must have 1 parameter", pos)
+        raise generic.ScriptError(f"{name}() must have 1 parameter", pos)
     if not isinstance(args[0], StringLiteral) or args[0].value not in table:
         raise generic.ScriptError(
             "Parameter for {}() must be a string literal that is also in your {} table".format(name, table_name), pos
@@ -502,7 +502,7 @@ def builtin_resolve_typelabel(name, args, pos, table_name=None):
 @builtin
 def builtin_reserve_sprites(name, args, pos):
     if len(args) != 1:
-        raise generic.ScriptError(name + "() must have 1 parameter", pos)
+        raise generic.ScriptError(f"{name}() must have 1 parameter", pos)
     count = args[0].reduce_constant()
     return GRMOp(nmlop.GRM_RESERVE, 0x08, count.value, lambda x: "{}({:d})".format(name, count.value), pos)
 
@@ -515,7 +515,7 @@ def builtin_industry_type(name, args, pos):
     @return The industry type in the format used by grfs (industry prop 0x16 and var 0x64)
     """
     if len(args) != 2:
-        raise generic.ScriptError(name + "() must have 2 parameters", pos)
+        raise generic.ScriptError(f"{name}() must have 2 parameters", pos)
 
     type = args[0].reduce_constant(global_constants.const_list).value
     if type not in (0, 1):
@@ -532,11 +532,11 @@ def builtin_industry_type(name, args, pos):
 @builtins("accept_cargo", "produce_cargo")
 def builtin_cargoexpr(name, args, pos):
     if len(args) < 1:
-        raise generic.ScriptError(name + "() must have 1 or more parameters", pos)
+        raise generic.ScriptError(f"{name}() must have 1 or more parameters", pos)
 
     if not isinstance(args[0], StringLiteral) or args[0].value not in global_constants.cargo_numbers:
         raise generic.ScriptError(
-            "First argument of " + name + "() must be a string literal that is also in your cargo table", pos
+            f"First argument of {name}() must be a string literal that is also in your cargo table", pos
         )
     cargotype = global_constants.cargo_numbers[args[0].value]
 
@@ -551,10 +551,10 @@ def builtin_cargoexpr(name, args, pos):
 @builtins("acos", "asin", "atan", "cos", "sin", "sqrt", "tan")
 def builtin_math(name, args, pos):
     if len(args) != 1:
-        raise generic.ScriptError(name + "() must have 1 parameter", pos)
+        raise generic.ScriptError(f"{name}() must have 1 parameter", pos)
     val = args[0].reduce()
     if not isinstance(val, (ConstantNumeric, ConstantFloat)):
-        raise generic.ScriptError("Parameter for " + name + "() must be a constant", pos)
+        raise generic.ScriptError(f"Parameter for {name}() must be a constant", pos)
     math_func_table = {
         "acos": math.acos,
         "asin": math.asin,
@@ -570,36 +570,36 @@ def builtin_math(name, args, pos):
 @builtin
 def builtin_round(name, args, pos):
     if len(args) != 1:
-        raise generic.ScriptError(name + "() must have 1 parameter", pos)
+        raise generic.ScriptError(f"{name}() must have 1 parameter", pos)
     val = args[0].reduce()
     if not isinstance(val, (ConstantNumeric, ConstantFloat)):
-        raise generic.ScriptError("Parameter for " + name + "() must be a constant", pos)
+        raise generic.ScriptError(f"Parameter for {name}() must be a constant", pos)
     return ConstantNumeric(round(val.value), pos)
 
 
 @builtin
 def builtin_int(name, args, pos):
     if len(args) != 1:
-        raise generic.ScriptError(name + "() must have 1 parameter", pos)
+        raise generic.ScriptError(f"{name}() must have 1 parameter", pos)
     val = args[0].reduce()
     if not isinstance(val, (ConstantNumeric, ConstantFloat)):
-        raise generic.ScriptError("Parameter for " + name + "() must be a constant", pos)
+        raise generic.ScriptError(f"Parameter for {name}() must be a constant", pos)
     return ConstantNumeric(int(val.value), val.pos)
 
 
 @builtin
 def builtin_abs(name, args, pos):
     if len(args) != 1:
-        raise generic.ScriptError(name + "() must have 1 parameter", pos)
+        raise generic.ScriptError(f"{name}() must have 1 parameter", pos)
     return AbsOp(args[0], args[0].pos).reduce()
 
 
 @builtin
 def builtin_sound(name, args, pos):
     if len(args) not in (1, 2):
-        raise generic.ScriptError(name + "() must have 1 or 2 parameters", pos)
+        raise generic.ScriptError(f"{name}() must have 1 or 2 parameters", pos)
     if not isinstance(args[0], StringLiteral):
-        raise generic.ScriptError("Parameter for " + name + "() must be a string literal", pos)
+        raise generic.ScriptError(f"Parameter for {name}() must be a string literal", pos)
     volume = args[1].reduce_constant().value if len(args) >= 2 else 100
     generic.check_range(volume, 0, 100, "sound volume", pos)
     from nml.actions import action11
@@ -610,7 +610,7 @@ def builtin_sound(name, args, pos):
 @builtin
 def builtin_import_sound(name, args, pos):
     if len(args) not in (2, 3):
-        raise generic.ScriptError(name + "() must have 2 or 3 parameters", pos)
+        raise generic.ScriptError(f"{name}() must have 2 or 3 parameters", pos)
     grfid = parse_string_to_dword(args[0].reduce())
     sound_num = args[1].reduce_constant().value
     volume = args[2].reduce_constant().value if len(args) >= 3 else 100
@@ -628,7 +628,7 @@ def builtin_relative_coord(name, args, pos):
     @return Coordinates in 0xYYXX format.
     """
     if len(args) != 2:
-        raise generic.ScriptError(name + "() must have x and y coordinates as parameters", pos)
+        raise generic.ScriptError(f"{name}() must have x and y coordinates as parameters", pos)
 
     if isinstance(args[0], ConstantNumeric):
         generic.check_range(args[0].value, 0, 255, "Argument of '{}'".format(name), args[0].pos)
@@ -652,7 +652,7 @@ def builtin_num_corners_raised(name, args, pos):
     @return Number of raised corners in a slope (4 for steep slopes)
     """
     if len(args) != 1:
-        raise generic.ScriptError(name + "() must have 1 parameter", pos)
+        raise generic.ScriptError(f"{name}() must have 1 parameter", pos)
 
     slope = args[0]
     # The returned value is ((slope x 0x8421) & 0x11111) % 0xF
@@ -676,7 +676,7 @@ def builtin_slope_to_sprite_offset(name, args, pos):
     @return sprite offset to use
     """
     if len(args) != 1:
-        raise generic.ScriptError(name + "() must have 1 parameter", pos)
+        raise generic.ScriptError(f"{name}() must have 1 parameter", pos)
 
     if isinstance(args[0], ConstantNumeric):
         generic.check_range(args[0].value, 0, 15, "Argument of '{}'".format(name), args[0].pos)
@@ -702,7 +702,7 @@ def builtin_palette_1cc(name, args, pos):
     @return Recolour sprite to use
     """
     if len(args) != 1:
-        raise generic.ScriptError(name + "() must have 1 parameter", pos)
+        raise generic.ScriptError(f"{name}() must have 1 parameter", pos)
 
     if isinstance(args[0], ConstantNumeric):
         generic.check_range(args[0].value, 0, 15, "Argument of '{}'".format(name), args[0].pos)
@@ -718,7 +718,7 @@ def builtin_palette_2cc(name, args, pos):
     @return Recolour sprite to use
     """
     if len(args) != 2:
-        raise generic.ScriptError(name + "() must have 2 parameters", pos)
+        raise generic.ScriptError(f"{name}() must have 2 parameters", pos)
 
     for i in range(0, 2):
         if isinstance(args[i], ConstantNumeric):
@@ -740,7 +740,7 @@ def builtin_vehicle_curv_info(name, args, pos):
     @return Value to use with vehicle var curv_info
     """
     if len(args) != 2:
-        raise generic.ScriptError(name + "() must have 2 parameters", pos)
+        raise generic.ScriptError(f"{name}() must have 2 parameters", pos)
 
     for arg in args:
         if isinstance(arg, ConstantNumeric):
@@ -759,11 +759,11 @@ def builtin_format_string(name, args, pos):
     @return Formatted string
     """
     if len(args) < 1:
-        raise generic.ScriptError(name + "() must have at least one parameter", pos)
+        raise generic.ScriptError(f"{name}() must have at least one parameter", pos)
 
     format = args[0].reduce()
     if not isinstance(format, StringLiteral):
-        raise generic.ScriptError(name + "() parameter 1 'format' must be a literal string", format.pos)
+        raise generic.ScriptError(f"{name}() parameter 1 'format' must be a literal string", format.pos)
 
     # Validate other args
     format_args = []
@@ -771,7 +771,7 @@ def builtin_format_string(name, args, pos):
         arg = arg.reduce()
         if not isinstance(arg, (StringLiteral, ConstantFloat, ConstantNumeric)):
             raise generic.ScriptError(
-                name + "() parameter {:d} is not a constant number of literal string".format(i + 1), arg.pos
+                f"{name}() parameter {i + 1:d} is not a constant number of literal string", arg.pos
             )
         format_args.append(arg.value)
 
@@ -779,7 +779,7 @@ def builtin_format_string(name, args, pos):
         result = format.value % tuple(format_args)
         return StringLiteral(result, pos)
     except Exception as ex:
-        raise generic.ScriptError("Invalid combination of format / arguments for {}: {}".format(name, str(ex)), pos)
+        raise generic.ScriptError(f"Invalid combination of format / arguments for {name}: {str(ex)}", pos)
 
 
 # }
diff --git a/nml/expression/identifier.py b/nml/expression/identifier.py
index 426bdb4b9..924086e83 100644
--- a/nml/expression/identifier.py
+++ b/nml/expression/identifier.py
@@ -74,7 +74,7 @@ def reduce(self, id_dicts=None, unknown_id_fatal=True, search_func_ptr=False):
                     return func(self.value, id_d[self.value], self.pos).reduce(id_dicts)
 
         if unknown_id_fatal and not ignore_all_invalid_ids:
-            raise generic.ScriptError("Unrecognized identifier '" + self.value + "' encountered", self.pos)
+            raise generic.ScriptError(f"Unrecognized identifier '{self.value}' encountered", self.pos)
 
         return self
 
diff --git a/nml/generic.py b/nml/generic.py
index a39180bce..c0e7096b8 100644
--- a/nml/generic.py
+++ b/nml/generic.py
@@ -248,7 +248,7 @@ def __init__(self, pos=None):
 class RangeError(ScriptError):
     def __init__(self, value, min_value, max_value, name, pos=None):
         ScriptError.__init__(
-            self, name + " out of range " + str(min_value) + ".." + str(max_value) + ", encountered " + str(value), pos
+            self, f"{name} out of range {str(min_value)}..{str(max_value)}, encountered {str(value)}", pos
         )