diff --git a/guppylang/module.py b/guppylang/module.py
index 28f16cd0..934c2b99 100644
--- a/guppylang/module.py
+++ b/guppylang/module.py
@@ -5,7 +5,6 @@
 from types import ModuleType
 from typing import Any, Union
 
-from guppylang.ast_util import AstNode
 from guppylang.checker.core import Globals, PyScope
 from guppylang.compiler.core import CompiledGlobals
 from guppylang.definition.common import (
@@ -104,6 +103,9 @@ def load(self, m: Union[ModuleType, "GuppyModule"]) -> None:
     def register_def(self, defn: RawDef, instance: TypeDef | None = None) -> None:
         """Registers a definition with this module.
 
+        If the name of the definition is already defined, the new definition
+        replaces the old.
+
         Optionally, the definition can be marked as an instance method by passing the
         corresponding instance type definition.
         """
@@ -111,7 +113,6 @@ def register_def(self, defn: RawDef, instance: TypeDef | None = None) -> None:
         if self._instance_func_buffer is not None and not isinstance(defn, TypeDef):
             self._instance_func_buffer[defn.name] = defn
         else:
-            self._check_name_available(defn.name, defn.defined_at)
             if isinstance(defn, TypeDef | ParamDef):
                 self._raw_type_defs[defn.id] = defn
             else:
@@ -228,13 +229,6 @@ def _check_not_yet_compiled(self) -> None:
         if self._compiled:
             raise GuppyError(f"The module `{self.name}` has already been compiled")
 
-    def _check_name_available(self, name: str, node: AstNode | None) -> None:
-        if self.contains(name):
-            raise GuppyError(
-                f"Module `{self.name}` already contains a definition named `{name}`",
-                node,
-            )
-
 
 def get_py_scope(f: PyFunc) -> PyScope:
     """Returns a mapping of all variables captured by a Python function.
diff --git a/tests/integration/test_redefinition.py b/tests/integration/test_redefinition.py
new file mode 100644
index 00000000..f7497a95
--- /dev/null
+++ b/tests/integration/test_redefinition.py
@@ -0,0 +1,19 @@
+from guppylang.decorator import guppy
+from guppylang.module import GuppyModule
+
+import guppylang.prelude.quantum as quantum
+
+
+def test_redefinition(validate):
+    module = GuppyModule("test")
+    module.load(quantum)
+
+    @guppy(module)
+    def test() -> bool:
+        return True
+
+    @guppy(module)
+    def test() -> bool:  # noqa: F811
+        return False
+
+    validate(module.compile())