diff --git a/dist/tools/ci/can_fast_ci_run.py b/dist/tools/ci/can_fast_ci_run.py
index 8c8dd8e645..56817d20de 100755
--- a/dist/tools/ci/can_fast_ci_run.py
+++ b/dist/tools/ci/can_fast_ci_run.py
@@ -73,6 +73,12 @@ class ChangeSet:
         while module != "":
             makefile = os.path.join(self._riotbase, module, "Makefile")
             if os.path.isfile(makefile) or module in EXCEPTION_MODULES:
+
+                # map all tests/unittests/* to just tests/unittests
+                # workaround for #18987
+                if module.startswith("tests/unittests/"):
+                    module = "tests/unittests"
+
                 if module in dest:
                     dest[module].append(file)
                 else: