diff --git a/tree-walk.c b/tree-walk.c
index 808bb55ba3f..4e1a7b6aa5c 100644
--- a/tree-walk.c
+++ b/tree-walk.c
@@ -549,7 +549,7 @@ static int match_entry(const struct name_entry *entry, int pathlen,
 	return 0;
 }
 
-static int match_dir_prefix(const char *base, int baselen,
+static int match_dir_prefix(const char *base,
 			    const char *match, int matchlen)
 {
 	if (strncmp(base, match, matchlen))
@@ -606,7 +606,7 @@ int tree_entry_interesting(const struct name_entry *entry,
 
 		if (baselen >= matchlen) {
 			/* If it doesn't match, move along... */
-			if (!match_dir_prefix(base_str, baselen, match, matchlen))
+			if (!match_dir_prefix(base_str, match, matchlen))
 				goto match_wildcards;
 
 			if (!ps->recursive || ps->max_depth == -1)
@@ -618,8 +618,8 @@ int tree_entry_interesting(const struct name_entry *entry,
 					      ps->max_depth);
 		}
 
-		/* Does the base match? */
-		if (!strncmp(base_str, match, baselen)) {
+		/* Either there must be no base, or the base must match. */
+		if (baselen == 0 || !strncmp(base_str, match, baselen)) {
 			if (match_entry(entry, pathlen,
 					match + baselen, matchlen - baselen,
 					&never_interesting))