diff --git a/graphify/extract.py b/graphify/extract.py
index 2c715ac36..d45b71d70 100644
--- a/graphify/extract.py
+++ b/graphify/extract.py
@@ -5048,6 +5048,8 @@ def _resolve_typescript_member_calls(
     # `updateHash` / `_updateHash` are two nodes of one class, so the exact
     # name is tried first and `_key` stays the fallback.
     method_exact: dict[tuple[str, str], str] = {}
+    # Keys more than one member normalizes to: the fallback can't tell them apart.
+    method_key_ambiguous: set[tuple[str, str]] = set()
     class_of_method: dict[str, str] = {}
     for e in all_edges:
         if e.get("relation") != "method":
@@ -5055,7 +5057,10 @@ def _resolve_typescript_member_calls(
         src, tgt = e.get("source"), e.get("target")
         tnode = node_by_id.get(tgt)
         if tnode is not None:
-            method_index[(src, _key(tnode.get("label", "")))] = tgt
+            key = (src, _key(tnode.get("label", "")))
+            if method_index.get(key, tgt) != tgt:
+                method_key_ambiguous.add(key)
+            method_index[key] = tgt
             method_exact[(src, str(tnode.get("label", "")).removesuffix("()").removeprefix("."))] = tgt
         if isinstance(src, str) and isinstance(tgt, str):
             class_of_method[tgt] = src
@@ -5188,7 +5193,7 @@ def _resolve_typescript_member_calls(
         type_nid = visible[0]
         method_nid = method_exact.get((type_nid, str(callee)))
         exact = method_nid is not None
-        if not exact:
+        if not exact and (type_nid, _key(callee)) not in method_key_ambiguous:
             method_nid = method_index.get((type_nid, _key(callee)))
         if not method_nid:
             # Receiver typed, but the type has no such method. The old fallback
diff --git a/tests/test_js_member_collisions.py b/tests/test_js_member_collisions.py
index c302b2604..b4acc9d03 100644
--- a/tests/test_js_member_collisions.py
+++ b/tests/test_js_member_collisions.py
@@ -99,6 +99,34 @@ def test_cross_file_ts_typed_receiver_hits_each_member(tmp_path):
     assert ("b()", ".$set()") in calls and ("b()", ".set()") not in calls
 
 
+
+@pytest.mark.parametrize("members,call", [
+    ("  close(): void {}\n  #close(): void {}\n", "c._close()"),
+    ("  updateHash(): void {}\n  _updateHash(): void {}\n", "c.$updateHash()"),
+    ("  updateHash(): void {}\n  _updateHash(): void {}\n", "c.UpdateHash()"),
+    ("  set(v: number): void {}\n  $set(v: number): void {}\n", "c._set(1)"),
+    ("  _a(): void {}\n  $a(): void {}\n", "c.a()"),
+])
+def test_cross_file_call_matching_no_member_exactly_is_not_guessed(tmp_path, members, call):
+    # Review on #4479: neither member has the called name, and the loose key fits
+    # both, so picking one would be a guess (it was whichever registered last).
+    r = _extract(tmp_path, {
+        "ctx.ts": "export class Ctx {\n" + members + "}\n",
+        "use.ts": ('import { Ctx } from "./ctx";\n'
+                   "export function go(c: Ctx) { " + call + "; }\n"),
+    })
+    assert not [t for s, t in _calls(r) if s == "go()"], _calls(r)
+
+
+def test_cross_file_loose_match_with_a_single_candidate_is_unchanged(tmp_path):
+    # One member per key still resolves loosely, as on v8 (not touched here).
+    r = _extract(tmp_path, {
+        "ctx.ts": "export class Ctx {\n  _close(): void {}\n}\n",
+        "use.ts": ('import { Ctx } from "./ctx";\n'
+                   "export function go(c: Ctx) { c.close(); }\n"),
+    })
+    assert ("go()", "._close()") in _calls(r)
+
 def test_dedup_build_and_merge_keep_both(tmp_path):
     from graphify.build import build, build_merge
     from graphify.cluster import cluster