diff --git a/_pytest/main.py b/_pytest/main.py
index 48f5bb6f2e2..5771a169999 100644
--- a/_pytest/main.py
+++ b/_pytest/main.py
@@ -687,7 +687,7 @@ def _tryconvertpyarg(self, x):
         # This method is sometimes invoked when AssertionRewritingHook, which
         # does not define a get_filename method, is already in place:
         try:
-            path = loader.get_filename()
+            path = loader.get_filename(x)
         except AttributeError:
             # Retrieve path from AssertionRewritingHook:
             path = loader.modules[x][0].co_filename