diff --git a/git-flow-release b/git-flow-release
index 8cdeadb..b75891e 100644
--- a/git-flow-release
+++ b/git-flow-release
@@ -105,9 +105,19 @@
 	fi
 }
 
+require_base_is_on_develop() {
+	if ! git branch --contains "$BASE" 2>/dev/null \
+			| sed 's/[* ] //g' \
+	  		| grep -q "^$DEVELOP_BRANCH\$"; then
+		die "fatal: Given base '$BASE' is not a valid commit on '$DEVELOP_BRANCH'."
+	fi
+}
+
 cmd_start() {
 	parse_args "$@"
+	BASE="${2:-$DEVELOP_BRANCH}"
 	require_version_arg
+	require_base_is_on_develop
 
 	# sanity checks
 	gitflow_require_clean_working_tree
@@ -118,11 +128,11 @@
 	gitflow_require_branch_absent $BRANCH
 
 	# create branch
-	git checkout -b $BRANCH $DEVELOP_BRANCH
+	git checkout -b $BRANCH $BASE
 
 	echo
 	echo "Summary of actions:"
-	echo "- A new branch '$BRANCH' was created, based on '$DEVELOP_BRANCH'"
+	echo "- A new branch '$BRANCH' was created, based on '$BASE'"
 	echo "- You are now on branch '$BRANCH'"
 	echo
 	echo "Follow-up actions:"
@@ -130,7 +140,7 @@
 	echo "- Start committing last-minute fixes in preparing your release"
 	echo "- When done, run:"
 	echo
-	echo "     git flow finish release '$VERSION'"
+	echo "     git flow release finish '$VERSION'"
 	echo
 }