diff --git a/tests/unit/cli/vyper_json/test_output_selection.py b/tests/unit/cli/vyper_json/test_output_selection.py
index a00b43aa75..3e1bc45494 100644
--- a/tests/unit/cli/vyper_json/test_output_selection.py
+++ b/tests/unit/cli/vyper_json/test_output_selection.py
@@ -116,7 +116,7 @@ def has_suffix_key(data: dict, suffix: str) -> bool:
                 return True
         return False
 
-    assert has_suffix_key(out, "<unknown>: foo")
+    assert has_suffix_key(out, "0: foo")
     assert has_suffix_key(out, "bar")
-    assert has_suffix_key(out, "A.vy: foo")
+    assert has_suffix_key(out, "1: foo")
     assert not has_suffix_key(out, "faa")
diff --git a/vyper/compiler/output.py b/vyper/compiler/output.py
index 1c73412aee..ef63c6839a 100644
--- a/vyper/compiler/output.py
+++ b/vyper/compiler/output.py
@@ -214,7 +214,7 @@ def build_metadata_output(compiler_data: CompilerData) -> dict:
     for fn_t in module_t.exposed_functions:
         assert isinstance(fn_t.ast_def, vy_ast.FunctionDef)
         for rif_t in fn_t.reachable_internal_functions:
-            sigs[rif_t.ast_def.module_node._metadata["type"]._id + ": " + rif_t.name] = rif_t
+            sigs[str(rif_t._ir_info.func_t._function_id) + ": " + rif_t.name] = rif_t
         sigs[fn_t.name] = fn_t
 
     def _var_rec_dict(variable_record):