diff --git a/scripts/truth.py b/scripts/truth.py
index d731dc54..d92cafd7 100644
--- a/scripts/truth.py
+++ b/scripts/truth.py
@@ -413,6 +413,7 @@ def generate_platform_truth(
         return norm_to_platform.get(normed, profile_sid)
 
     systems: dict[str, dict] = {}
+    unattributed: dict[str, int] = {}
     cores_profiled: set[str] = set()
     cores_unprofiled: set[str] = set()
     # Track which cores contribute to each system
@@ -429,12 +430,30 @@ def generate_platform_truth(
             profile, runs_standalone(emu_name, profile, standalone_set)
         ))
 
+        on_platform = {
+            _map_sys_id(sid) for sid in profile.get("systems", [])
+        } & platform_sys_ids
         for fe in filtered:
             profile_sid = fe.get("system", "")
-            if not profile_sid:
-                sys_ids = profile.get("systems", [])
-                profile_sid = sys_ids[0] if sys_ids else "unknown"
-            sys_id = _map_sys_id(profile_sid, fe.get("name", ""))
+            sys_ids = profile.get("systems", [])
+            if profile_sid:
+                sys_id = _map_sys_id(profile_sid, fe.get("name", ""))
+            elif len(sys_ids) <= 1:
+                sys_id = _map_sys_id(sys_ids[0] if sys_ids else "unknown", fe.get("name", ""))
+            else:
+                # A multi-system profile's entry without a system: the
+                # platform's own declaration of the name decides, or the one
+                # profile system the platform has. Otherwise it is not filed:
+                # the first system was a guess, and CLK's Apple, Mac, ZX and
+                # Amiga ROMs went to RomM as Amstrad CPC firmware.
+                declared = file_to_plat_sys.get(fe.get("name", "").lower())
+                if declared:
+                    sys_id = declared
+                elif len(on_platform) == 1:
+                    sys_id = next(iter(on_platform))
+                else:
+                    unattributed[emu_name] = unattributed.get(emu_name, 0) + 1
+                    continue
             system = systems.setdefault(sys_id, {})
             _merge_file_into_system(system, fe, emu_name, db)
             # Track core contribution per system
@@ -506,6 +525,9 @@ def generate_platform_truth(
             "cores_resolved": len(resolved),
             "cores_profiled": len(cores_profiled),
             "cores_unprofiled": sorted(cores_unprofiled),
+            # Entries of multi-system cores no system of this platform can
+            # be said to own: counted, never filed under a guess.
+            "unattributed": dict(sorted(unattributed.items())),
         },
     }
 
diff --git a/tests/test_truth_layout.py b/tests/test_truth_layout.py
index f646ba2b..031f673c 100644
--- a/tests/test_truth_layout.py
+++ b/tests/test_truth_layout.py
@@ -95,5 +95,41 @@ class AnArchiveStandsForItsMembers(unittest.TestCase):
         self.assertEqual([(f["name"], f["size"]) for f in dreamcast], [("boot.bin", 2097152)])
         self.assertEqual(dreamcast[0]["_cores"], ["retrodream"])
 
+
+class AnUnattributedEntryIsNotGuessed(unittest.TestCase):
+    """CLK names twenty-three machines and none of its ROMs says which: all
+    of them went under amstrad-cpc, its first system, and the RomM export
+    listed Apple, Mac, ZX and Amiga firmware as Amstrad CPC firmware."""
+
+    PROFILE = {
+        "emulator": "CLK", "type": "libretro",
+        "systems": ["amstrad-cpc", "apple-ii", "sinclair-zx81"],
+        "files": [{"name": "apple2gs.rom", "size": 131072},
+                  {"name": "zx81.rom", "size": 8192}],
+    }
+
+    def truth(self, systems):
+        config = {"cores": ["clk"], "systems": systems}
+        return generate_platform_truth("p", config, {}, {"clk": self.PROFILE})
+
+    def test_several_candidate_systems_file_nothing(self):
+        truth = self.truth({"amstrad-cpc": {"files": []}, "apple-ii": {"files": []}})
+        self.assertEqual(_names(truth), set())
+        self.assertEqual(truth["_coverage"]["unattributed"], {"clk": 2})
+
+    def test_the_platform_declaration_decides(self):
+        truth = self.truth({"amstrad-cpc": {"files": []},
+                            "apple-ii": {"files": [{"name": "apple2gs.rom"}]}})
+        self.assertEqual(
+            [f["name"] for f in truth["systems"]["apple-ii"]["files"]], ["apple2gs.rom"]
+        )
+
+    def test_one_candidate_system_takes_them(self):
+        truth = self.truth({"sinclair-zx81": {"files": []}})
+        self.assertEqual(
+            sorted(f["name"] for f in truth["systems"]["sinclair-zx81"]["files"]),
+            ["apple2gs.rom", "zx81.rom"],
+        )
+
 if __name__ == "__main__":
     unittest.main()