diff --git a/update_git.sh b/update_git.sh
index 78e1d8e0..a0cc0b0f 100644
--- a/update_git.sh
+++ b/update_git.sh
@@ -60,7 +60,9 @@ rm -rf $GIT_DIR
 # Process patches to eliminate useless differences: limit file names to 40 chars
 # before extension and remove git signature. ('30' below gets us past dir prefix)
     for i in $CMP_DIR/*; do
-        head -n -3 $i > $CMP_DIR/${i:30:40}.patch
+        # format-patch may append a signature, which per default contains the git version
+        # wipe everything starting from the signature tag
+        sed '/^-- $/Q' $i > $CMP_DIR/${i:30:40}.patch
         rm $i
     done