diff --git a/git-pull.sh b/git-pull.sh
index 2c7f432dc04254dcb9906f4d078eb16d195848ca..25adddfddfc0a7e2cc33ea0dc1e1d7a101514972 100755
--- a/git-pull.sh
+++ b/git-pull.sh
@@ -171,6 +171,11 @@ case "$merge_head" in
 		echo >&2 "Cannot merge multiple branches into empty head"
 		exit 1
 	fi
+	if test true = "$rebase"
+	then
+		echo >&2 "Cannot rebase onto multiple branches"
+		exit 1
+	fi
 	;;
 esac
 
diff --git a/git-rebase.sh b/git-rebase.sh
index 6d3eddbada5e1a5a38e2b909c75909b8e9d5fda8..368c0ef4342df990a5617fd6fbe2cd973b1b208b 100755
--- a/git-rebase.sh
+++ b/git-rebase.sh
@@ -310,6 +310,7 @@ do
 	esac
 	shift
 done
+test $# -gt 2 && usage
 
 # Make sure we do not have $GIT_DIR/rebase-apply
 if test -z "$do_merge"