diff --git a/tests/unit/cli/vyper_json/test_get_inputs.py b/tests/unit/cli/vyper_json/test_get_inputs.py
index c91cc750f2..7a6901bfd1 100644
--- a/tests/unit/cli/vyper_json/test_get_inputs.py
+++ b/tests/unit/cli/vyper_json/test_get_inputs.py
@@ -92,8 +92,8 @@ def test_interface_collision():
         "sources": {"foo.vy": {"content": FOO_CODE}},
         "interfaces": {"bar.json": {"abi": BAR_ABI}, "bar.vy": {"content": BAR_CODE}},
     }
-    with pytest.raises(JSONError):
-        get_inputs(input_json)
+    # don't throw, bar.json and bar.vy have different paths
+    get_inputs(input_json)
 
 
 def test_json_no_abi():
diff --git a/vyper/cli/vyper_json.py b/vyper/cli/vyper_json.py
index 750afcb88e..cc3e2ce3fc 100755
--- a/vyper/cli/vyper_json.py
+++ b/vyper/cli/vyper_json.py
@@ -160,7 +160,8 @@ def get_inputs(input_dict: dict) -> dict[PurePath, Any]:
     seen = {}
 
     for path, value in input_dict["sources"].items():
-        path = PurePath(path)
+        path = PurePath(_normpath(path))
+
         if "urls" in value:
             raise JSONError(f"{path} - 'urls' is not a supported field, use 'content' instead")
         if "content" not in value:
@@ -171,17 +172,17 @@ def get_inputs(input_dict: dict) -> dict[PurePath, Any]:
                 raise JSONError(
                     f"Calculated keccak of '{path}' does not match keccak given in input JSON"
                 )
-        if path.stem in seen:
+        if path in seen:
             raise JSONError(f"Contract namespace collision: {path}")
 
         # value looks like {"content": <source code>}
         # this will be interpreted by JSONInputBundle later
         ret[path] = value
-        seen[path.stem] = True
+        seen[path] = True
 
     for path, value in input_dict.get("interfaces", {}).items():
-        path = PurePath(path)
-        if path.stem in seen:
+        path = PurePath(_normpath(path))
+        if path in seen:
             raise JSONError(f"Interface namespace collision: {path}")
 
         if isinstance(value, list):
@@ -208,7 +209,7 @@ def get_inputs(input_dict: dict) -> dict[PurePath, Any]:
             )
 
         ret[path] = value
-        seen[path.stem] = True
+        seen[path] = True
 
     return ret