diff --git a/config.c b/config.c
index a30cb5c07db18a5ac16c1c98b6600c9fe6dc1b73..491a9050aebdeff2ca081cf6d6652188c0a77e1d 100644
--- a/config.c
+++ b/config.c
@@ -826,9 +826,13 @@ static int git_default_core_config(const char *var, const char *value)
 	if (!strcmp(var, "core.commentchar")) {
 		const char *comment;
 		int ret = git_config_string(&comment, var, value);
-		if (!ret)
+		if (ret)
+			return ret;
+		else if (comment[0] && !comment[1]) {
 			comment_line_char = comment[0];
-		return ret;
+		} else
+			return error("core.commentChar should only be one character");
+		return 0;
 	}
 
 	if (!strcmp(var, "core.askpass"))
diff --git a/t/t7508-status.sh b/t/t7508-status.sh
index c987b5ed652b977cc2169bdd4c64f42eccdf63db..148ab9ebc2fe24fff055d7af9662ef6bde5c6414 100755
--- a/t/t7508-status.sh
+++ b/t/t7508-status.sh
@@ -1350,8 +1350,7 @@ test_expect_success "status (core.commentchar with submodule summary)" '
 
 test_expect_success "status (core.commentchar with two chars with submodule summary)" '
 	test_config core.commentchar ";;" &&
-	git -c status.displayCommentPrefix=true status >output &&
-	test_i18ncmp expect output
+	test_must_fail git -c status.displayCommentPrefix=true status
 '
 
 test_expect_success "--ignore-submodules=all suppresses submodule summary" '