diff --git a/builtin/grep.c b/builtin/grep.c
index e83b33bdaa..c4c6325941 100644
--- a/builtin/grep.c
+++ b/builtin/grep.c
@@ -1176,6 +1176,12 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
 			break;
 		}
 
+		if (!use_index) {
+			if (seen_dashdash)
+				die(_("--no-index cannot be used with revs"));
+			break;
+		}
+
 		if (get_sha1_with_context(arg, 0, sha1, &oc)) {
 			if (seen_dashdash)
 				die(_("unable to resolve revision: %s"), arg);
diff --git a/t/t7810-grep.sh b/t/t7810-grep.sh
index a6011f9b1d..c051c7ee80 100755
--- a/t/t7810-grep.sh
+++ b/t/t7810-grep.sh
@@ -1030,6 +1030,19 @@ test_expect_success 'grep --no-index pattern -- path' '
 	)
 '
 
+test_expect_success 'grep --no-index complains of revs' '
+	test_must_fail git grep --no-index o master -- 2>err &&
+	test_i18ngrep "no-index cannot be used with revs" err
+'
+
+test_expect_success 'grep --no-index prefers paths to revs' '
+	test_when_finished "rm -f master" &&
+	echo content >master &&
+	echo master:content >expect &&
+	git grep --no-index o master >actual &&
+	test_cmp expect actual
+'
+
 cat >expected <<EOF
 hello.c:int main(int argc, const char **argv)
 hello.c:	printf("Hello world.\n");