diff --git a/tools/releasetools/check_target_files_signatures.py b/tools/releasetools/check_target_files_signatures.py
index dd57033..5c541ab 100755
--- a/tools/releasetools/check_target_files_signatures.py
+++ b/tools/releasetools/check_target_files_signatures.py
@@ -331,7 +331,7 @@
 
     by_certpair = {}
 
-    for i in all:
+    for i in all_apks:
       if i in self.apks:
         if i in other.apks:
           # in both; should have same set of certs