diff --git a/git-difftool--helper.sh b/git-difftool--helper.sh
index 3d0fe0cd93..b00ed95dba 100755
--- a/git-difftool--helper.sh
+++ b/git-difftool--helper.sh
@@ -40,7 +40,7 @@ launch_merge_tool () {
 	# the user with the real $MERGED name before launching $merge_tool.
 	if should_prompt
 	then
-		printf "\nViewing: '$MERGED'\n"
+		printf "\nViewing: '%s'\n" "$MERGED"
 		if use_ext_cmd
 		then
 			printf "Launch '%s' [Y/n]: " \
diff --git a/git-mergetool.sh b/git-mergetool.sh
index c50e18a899..012afa5549 100755
--- a/git-mergetool.sh
+++ b/git-mergetool.sh
@@ -440,7 +440,7 @@ then
 fi
 
 printf "Merging:\n"
-printf "$files\n"
+printf "%s\n" "$files"
 
 IFS='
 '