diff --git a/tests/test_buffer.py b/tests/test_buffer.py
index 3a9db68..21720ea 100644
--- a/tests/test_buffer.py
+++ b/tests/test_buffer.py
@@ -4,6 +4,7 @@
 # ########################################### #
 
 import numpy as np
+import pytest
 
 import xobjects as xo
 from xobjects.test_helpers import for_all_test_contexts, requires_context
@@ -94,6 +95,35 @@ def test_free_simple(test_context):
         ch.free_string(offset)
         ch.check()
 
+@for_all_test_contexts
+def test_free(test_context):
+    class CheckFree(xo.Struct):
+        a = xo.Float64
+    ch = CheckFree(a=5, _context=test_context)
+    assert ch._buffer.capacity == 8
+    assert ch._buffer.chunks == []
+    with pytest.raises(ValueError, match="Cannot free outside of buffer"):
+        ch._buffer.free(-2, 8)
+    with pytest.raises(ValueError, match="Cannot free outside of buffer"):
+        ch._buffer.free(0, 10)
+    with pytest.raises(ValueError, match="Cannot free outside of buffer"):
+        ch._buffer.free(7,2)
+    ch._buffer.free(0,4)
+    assert len(ch._buffer.chunks) == 1
+    assert ch._buffer.chunks[0].start == 0
+    assert ch._buffer.chunks[0].end == 4
+    ch._buffer.free(0,4)  # Does nothing
+    ch._buffer.free(2,4)  # Increases free chunk
+    assert len(ch._buffer.chunks) == 1
+    assert ch._buffer.chunks[0].start == 0
+    assert ch._buffer.chunks[0].end == 6
+    ch._buffer.free(7,1)
+    assert len(ch._buffer.chunks) == 2
+    assert ch._buffer.chunks[0].start == 0
+    assert ch._buffer.chunks[0].end == 6
+    assert ch._buffer.chunks[1].start == 7
+    assert ch._buffer.chunks[1].end == 8
+
 
 @for_all_test_contexts
 def test_grow(test_context):
diff --git a/xobjects/context.py b/xobjects/context.py
index 4ac80e7..bcd03db 100644
--- a/xobjects/context.py
+++ b/xobjects/context.py
@@ -472,9 +472,13 @@ def grow(self, capacity):
         self.capacity = newcapacity
 
     def free(self, offset, size):
+        if offset < 0 or offset + size > self.capacity:
+            raise ValueError("Cannot free outside of buffer")
         nch = Chunk(offset, offset + size)
         # insert sorted
-        if offset > self.chunks[-1].start:  # new chuck at the end
+        if len(self.chunks) == 0:
+            self.chunks.append(nch)
+        elif offset > self.chunks[-1].start:  # new chuck at the end
             self.chunks.append(nch)
         else:  # new chuck needs to be inserted
             for ic, ch in enumerate(self.chunks):