diff --git a/filters/syntax-highlighting.sh b/filters/syntax-highlighting.sh
index 47f6267..24f6bb4 100755
--- a/filters/syntax-highlighting.sh
+++ b/filters/syntax-highlighting.sh
@@ -53,7 +53,7 @@ EXTENSION="${BASENAME##*.}"
 # found (for example) on EPEL 6.
 #
 # This is for version 2
-exec highlight --force -f -I -X -S $EXTENSION 2>/dev/null
+exec highlight --force -f -I -X -S "$EXTENSION" 2>/dev/null
 
 # This is for version 3
-#exec highlight --force -f -I -O xhtml -S $EXTENSION 2>/dev/null
+#exec highlight --force -f -I -O xhtml -S "$EXTENSION" 2>/dev/null