diff --git a/scripts/tags.sh b/scripts/tags.sh
index 0d6004e20658e27b519874ac01c2499572906175..cf7b12fee573174c8aaf00ee75aa9d21c056d61d 100755
--- a/scripts/tags.sh
+++ b/scripts/tags.sh
@@ -254,6 +254,6 @@ case "$1" in
 esac
 
 # Remove structure forward declarations.
-if [ -n $remove_structs ]; then
+if [ -n "$remove_structs" ]; then
     LANG=C sed -i -e '/^\([a-zA-Z_][a-zA-Z0-9_]*\)\t.*\t\/\^struct \1;.*\$\/;"\tx$/d' $1
 fi