diff --git a/builtin/diff.c b/builtin/diff.c
index b19530c996..d0e187ec18 100644
--- a/builtin/diff.c
+++ b/builtin/diff.c
@@ -269,8 +269,10 @@ static int builtin_diff_files(struct rev_info *revs, int argc, const char **argv
 			options |= DIFF_SILENT_ON_REMOVED;
 		else if (!strcmp(argv[1], "-h"))
 			usage(builtin_diff_usage);
-		else
-			return error(_("invalid option: %s"), argv[1]);
+		else {
+			error(_("invalid option: %s"), argv[1]);
+			usage(builtin_diff_usage);
+		}
 		argv++; argc--;
 	}
 
diff --git a/t/t4017-diff-retval.sh b/t/t4017-diff-retval.sh
index 5bc28ad9f0..f439f469bd 100755
--- a/t/t4017-diff-retval.sh
+++ b/t/t4017-diff-retval.sh
@@ -138,4 +138,9 @@ test_expect_success 'check honors conflict marker length' '
 	git reset --hard
 '
 
+test_expect_success 'option errors are not confused by --exit-code' '
+	test_must_fail git diff --exit-code --nonsense 2>err &&
+	grep '^usage:' err
+'
+
 test_done