diff --git a/git-flow-support b/git-flow-support
index 07c9ed2..1f5918f 100644
--- a/git-flow-support
+++ b/git-flow-support
@@ -67,12 +67,12 @@
 			if [ "$branch_sha" = "$master_sha" ]; then
 				printf "(no commits yet)"
 			else
-				typeset tagname=$(git name-rev --tags --no-undefined --name-only $base)
+				typeset tagname=$(git name-rev --tags --no-undefined --name-only "$base")
 				typeset nicename
 				if [ "$tagname" != "" ]; then
 					nicename=$tagname
 				else
-					nicename=$(git rev-parse --short $base)
+					nicename=$(git rev-parse --short "$base")
 				fi
 				printf "(based on $nicename)"
 			fi
@@ -135,9 +135,9 @@
 
 	# fetch remote changes
 	if flag fetch; then
-		git fetch -q $ORIGIN $BASE
+		git fetch -q "$ORIGIN" "$BASE"
 	fi
-	gitflow_require_branch_absent $BRANCH
+	gitflow_require_branch_absent "$BRANCH"
 
 	# create branch
 	git checkout -b "$BRANCH" "$BASE"