diff --git a/attr.c b/attr.c
index f6b3f7e850..924b4408d5 100644
--- a/attr.c
+++ b/attr.c
@@ -573,7 +573,8 @@ static void prepare_attr_stack(const char *path, int dirlen)
 
 		elem = attr_stack;
 		if (namelen <= dirlen &&
-		    !strncmp(elem->origin, path, namelen))
+		    !strncmp(elem->origin, path, namelen) &&
+		    (!namelen || path[namelen] == '/'))
 			break;
 
 		debug_pop(elem);
diff --git a/t/t0003-attributes.sh b/t/t0003-attributes.sh
index ebbc7554a7..61b5a2eba6 100755
--- a/t/t0003-attributes.sh
+++ b/t/t0003-attributes.sh
@@ -60,6 +60,16 @@ test_expect_success 'attribute test' '
 
 '
 
+test_expect_success 'prefixes are not confused with leading directories' '
+	attr_check a_plus/g unspecified &&
+	cat >expect <<-\EOF &&
+	a/g: test: a/g
+	a_plus/g: test: unspecified
+	EOF
+	git check-attr test a/g a_plus/g >actual &&
+	test_cmp expect actual
+'
+
 test_expect_success 'core.attributesfile' '
 	attr_check global unspecified &&
 	git config core.attributesfile "$HOME/global-gitattributes" &&