diff --git a/nle/tests/test_converter.py b/nle/tests/test_converter.py
index 70ca6f98a..7a078be1b 100644
--- a/nle/tests/test_converter.py
+++ b/nle/tests/test_converter.py
@@ -190,6 +190,12 @@ def test_noexist(self):
         ):
             converter.load_ttyrec(fn)
 
+    def test_rejects_zero_rows_or_cols(self):
+        with pytest.raises(ValueError, match=r"rows and cols must be > 0"):
+            Converter(0, COLUMNS, TTYREC_V3, ROWS, COLUMNS)
+        with pytest.raises(ValueError, match=r"rows and cols must be > 0"):
+            Converter(ROWS, 0, TTYREC_V3, ROWS, COLUMNS)
+
     def test_illegal_buffers(self):
         converter = Converter(ROWS, COLUMNS, TTYREC_V1)
         converter.load_ttyrec(getfilename(TTYREC_2020))
@@ -284,6 +290,18 @@ def test_illegal_buffers(self):
         with pytest.raises(ValueError, match=r"Numpy array required"):
             converter.convert(chars, colors, cursors, timestamps, actions, scores)
 
+        chars = np.array(8, dtype=np.uint8)
+        colors = np.zeros((10, ROWS, COLUMNS), dtype=np.int8)
+        cursors = np.zeros((10, 2), dtype=np.int16)
+        actions = np.zeros((10), dtype=np.uint8)
+        timestamps = np.zeros((10,), dtype=np.int64)
+        scores = np.zeros((10), dtype=np.int32)
+        with pytest.raises(
+            ValueError,
+            match=r"Array has wrong number of dimensions \(expected 3, got 0\)",
+        ):
+            converter.convert(chars, colors, cursors, timestamps, actions, scores)
+
         chars = np.zeros((10, ROWS, COLUMNS), dtype=np.uint8)
         timestamps = [0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
         with pytest.raises(ValueError, match=r"Numpy array required"):
diff --git a/third_party/converter/converter.c b/third_party/converter/converter.c
index eae901f7d..7103050d4 100644
--- a/third_party/converter/converter.c
+++ b/third_party/converter/converter.c
@@ -186,6 +186,10 @@ Conversion *conversion_create(size_t rows, size_t cols, size_t term_rows,
     stripgfx_init = true;
   }
 
+  if (rows == 0 || cols == 0) {
+    return NULL;
+  }
+
   Conversion *c = malloc(sizeof(Conversion));
   if (!c) return NULL;
   c->version = version;
@@ -193,6 +197,10 @@ Conversion *conversion_create(size_t rows, size_t cols, size_t term_rows,
   c->cols = cols;
   if (!term_rows) term_rows = rows;
   if (!term_cols) term_cols = cols;
+  if (term_rows < rows || term_cols < cols) {
+    free(c);
+    return NULL;
+  }
   assert(rows <= term_rows && cols <= term_cols);
   c->chars = (UnsignedCharPtr){0};
   c->colors = (SignedCharPtr){0};
diff --git a/third_party/converter/pyconverter.cc b/third_party/converter/pyconverter.cc
index 2d4d5d751..ba4a06ce1 100644
--- a/third_party/converter/pyconverter.cc
+++ b/third_party/converter/pyconverter.cc
@@ -65,6 +65,9 @@ class Converter
           term_rows_((term_rows != 0) ? term_rows : rows),
           term_cols_((term_cols != 0) ? term_cols : cols)          
     {
+        if (rows_ == 0 || cols_ == 0)
+            throw std::invalid_argument("rows and cols must be > 0");
+
         if (term_rows_ < 2 || term_cols_ < 2)
            throw std::invalid_argument("Terminal invalid: term_rows and term_cols must be >1");
 
@@ -117,7 +120,14 @@ class Converter
         py::array array = py::array::ensure(chars);
         if (!array.dtype().is(py::dtype::of<uint8_t>()))
             throw std::invalid_argument("Buffer dtype mismatch.");
-        size_t unroll = array.request().shape[0];
+        py::buffer_info chars_buf = array.request();
+        if (chars_buf.ndim != 3) {
+            std::ostringstream ss;
+            ss << "Array has wrong number of dimensions (expected 3, got "
+               << chars_buf.ndim << ")";
+            throw std::invalid_argument(ss.str());
+        }
+        size_t unroll = chars_buf.shape[0];
 
         conversion_set_buffers(
             conversion_,
@@ -207,4 +217,4 @@ PYBIND11_MODULE(_pyconverter, m)
         .def_property_readonly("filename", &Converter::filename)
         .def_property_readonly("part", &Converter::part)
         .def_property_readonly("gameid", &Converter::gameid);
-}
\ No newline at end of file
+}