diff --git a/emulators/gam4980.yml b/emulators/gam4980.yml
index 71aeec45..8d266bb1 100644
--- a/emulators/gam4980.yml
+++ b/emulators/gam4980.yml
@@ -16,14 +16,13 @@ systems:
 # Original code from https://codeberg.org/iyzsong/gam4980, based on the
 # BA4988 BBK simulator by Wuyun. Uses a 6502-based CPU with banked ROM access.
 #
-# ROM loading (libretro.c:692-760, sys_init):
+# ROM loading (src/libretro.c:707-746, sys_init):
 #   Opens romdir/8.BIN and reads 0x200000 bytes (2 MB) into sys.rom_8 (font ROM).
 #   Opens romdir/E.BIN and reads 0x200000 bytes (2 MB) into sys.rom_e (OS ROM).
-#   The upstream has error handling (error_msg + RETRO_ENVIRONMENT_SHUTDOWN on
-#   missing files). The fork (ThisBoringWorld) removed these checks -- crashes
-#   on missing files.
+#   A missing file shows "GAM4980: Missing 8.BIN" (or E.BIN) and the core
+#   shuts down through RETRO_ENVIRONMENT_SHUTDOWN.
 #
-# Memory map (libretro.c:109-110, 300-305):
+# Memory map (src/libretro.c:109-110, 302-305):
 #   0x800000-0x9FFFFF  rom_8 (font ROM, 8.BIN)
 #   0xE00000-0xFFFFFF  rom_e (OS ROM, E.BIN)
 #
@@ -42,19 +41,19 @@ files:
     required: true
     system: bbk-longman-4980
     note: "Font ROM (2 MB). Loaded at 0x800000."
-    source_ref: "libretro.c:716-718"
+    source_ref: "src/libretro.c:730-737"
 
   - name: "gam4980/E.BIN"
     size: 2097152
     required: true
     system: bbk-longman-4980
     note: "OS ROM (2 MB). Loaded at 0xE00000."
-    source_ref: "libretro.c:720-722"
+    source_ref: "src/libretro.c:739-746"
 
 platform_details:
   bios_mapping:
     target: "0x800000-0x9FFFFF (font), 0xE00000-0xFFFFFF (OS) in banked address space"
-    source_ref: "libretro.c:109-110, 300-305"
+    source_ref: "src/libretro.c:109-110, 302-305"
     note: |
       sys.rom_8 and sys.rom_e are flat 2 MB arrays. The CPU accesses them
       through bank-switched memory (PA() macro resolves virtual to physical
@@ -62,7 +61,7 @@ platform_details:
       the banking system.
 
   load_path:
-    source_ref: "libretro.c:1173-1175"
+    source_ref: "src/libretro.c:1193-1197"
     note: |
       retro_init() builds the path as {system_directory}/gam4980/ and
       passes it to sys_init(). Files must be named exactly 8.BIN and
diff --git a/scripts/profile_sync.py b/scripts/profile_sync.py
index d7cb053f..fa610a97 100644
--- a/scripts/profile_sync.py
+++ b/scripts/profile_sync.py
@@ -2861,6 +2861,18 @@ def bump_commit(
         # Rewriting the pin to the value it already holds is not a bump, and
         # announcing it buries the profiles that did move.
         return False
+    if (
+        document.get("source_commit") != report.head
+        and not cites_primary(report)
+    ):
+        # Every ref anchored in another repository: HEAD of this one was
+        # never compared with anything. gam4980's pin moved to the fork's
+        # HEAD while its bare libretro.c refs still described upstream.
+        print(
+            f"{path.stem}: no ref resolves in {report.repo}, its pin is not advanced",
+            file=sys.stderr,
+        )
+        return False
     expected = dict(document)
     expected["source_commit"] = report.head
     new_text = _set_pin(text, document, "source_commit", report.head, "profiled_date")
@@ -2873,6 +2885,22 @@ def bump_commit(
     return True
 
 
+def cites_primary(report: ProfileReport) -> bool:
+    """Whether a ref resolved in the repository source_commit pins.
+
+    A part attributed to another declared repository carries its slug; one
+    read in the primary carries none. A profile citing nothing proves
+    nothing either way and is not held back.
+    """
+    if len(report.repos) < 2:
+        return True
+    parts = [
+        part for entry in report.entries for part in entry.parts
+        if part.status != "EXTERNAL"
+    ]
+    return not parts or any(part.repo is None for part in parts)
+
+
 def _set_pin(text: str, document: dict, field: str, value: str, after: str) -> str:
     """Write *field* as *value*, replacing its line or adding one after *after*."""
     current = document.get(field)
diff --git a/tests/test_profile_sync.py b/tests/test_profile_sync.py
index c03fd554..a76ab851 100644
--- a/tests/test_profile_sync.py
+++ b/tests/test_profile_sync.py
@@ -2772,6 +2772,24 @@ class TestBumpCommit(unittest.TestCase):
         self.assertEqual(profile_sync.pending_recale(report), 0)
         self.assertTrue(bump_commit(self.path, report))
 
+    def test_refused_when_no_ref_reads_the_pinned_repository(self):
+        """gam4980: every bare libretro.c ref anchored in upstream, and the
+        bump wrote the fork's HEAD over refs that never described it."""
+        def report(repo):
+            part = PartResult(
+                RefPart("libretro.c", 10, 12, "libretro.c:10-12"), "ANCHORED",
+                None, 10, 12, [], None, repo,
+            )
+            return ProfileReport(
+                name="p", repo="fork/n", repos=["fork/n", "up/n"], pin="pin",
+                head="newhead",
+                entries=[EntryReport("a.bin", "libretro.c:10-12", "ANCHORED", [part])],
+                counts={"ANCHORED": 1},
+            )
+        self.assertFalse(bump_commit(self.path, report("up/n")))
+        self.assertNotIn("newhead", self.path.read_text())
+        self.assertTrue(bump_commit(self.path, report(None)))
+
     def test_a_bump_alone_waits_for_the_recale(self):
         """lrps2 at 0 to review with two SHIFTED parts: --bump-commit run
         alone wrote the new pin over refs still on the old lines."""