diff --git a/capa/features/extractors/binexport2/__init__.py b/capa/features/extractors/binexport2/__init__.py
index 7fc32be71..da7bbcaf3 100644
--- a/capa/features/extractors/binexport2/__init__.py
+++ b/capa/features/extractors/binexport2/__init__.py
@@ -273,7 +273,7 @@ def _compute_thunks(self):
                 # because either, len is:
                 #    0 and the thunk doesn't point to anything, or
                 #   >1 and the thunk may end up at many functions.
-                assert len(thunk_callees) == 1
+                assert len(thunk_callees) == 1, f"thunk @ {hex(addr)} failed"
 
                 thunked_idx: int = thunk_callees[0]
                 thunked_vertex: BinExport2.CallGraph.Vertex = self.be2.call_graph.vertex[thunked_idx]