diff --git a/builtin/grep.c b/builtin/grep.c
index 2cd06126d2..2fc51fa2dc 100644
--- a/builtin/grep.c
+++ b/builtin/grep.c
@@ -542,18 +542,19 @@ static int grep_cache(struct grep_opt *opt, const struct pathspec *pathspec, int
 static int grep_tree(struct grep_opt *opt, const struct pathspec *pathspec,
 		     struct tree_desc *tree, struct strbuf *base, int tn_len)
 {
-	int hit = 0, match = 0;
+	int hit = 0;
+	enum interesting match = entry_not_interesting;
 	struct name_entry entry;
 	int old_baselen = base->len;
 
 	while (tree_entry(tree, &entry)) {
 		int te_len = tree_entry_len(&entry);
 
-		if (match != 2) {
+		if (match != all_entries_interesting) {
 			match = tree_entry_interesting(&entry, base, tn_len, pathspec);
-			if (match < 0)
+			if (match == all_entries_not_interesting)
 				break;
-			if (match == 0)
+			if (match == entry_not_interesting)
 				continue;
 		}
 
diff --git a/list-objects.c b/list-objects.c
index 39d80c0175..3dd4a96019 100644
--- a/list-objects.c
+++ b/list-objects.c
@@ -71,7 +71,8 @@ static void process_tree(struct rev_info *revs,
 	struct tree_desc desc;
 	struct name_entry entry;
 	struct name_path me;
-	int match = revs->diffopt.pathspec.nr == 0 ? 2 : 0;
+	enum interesting match = revs->diffopt.pathspec.nr == 0 ?
+		all_entries_interesting: entry_not_interesting;
 	int baselen = base->len;
 
 	if (!revs->tree_objects)
@@ -97,12 +98,12 @@ static void process_tree(struct rev_info *revs,
 	init_tree_desc(&desc, tree->buffer, tree->size);
 
 	while (tree_entry(&desc, &entry)) {
-		if (match != 2) {
+		if (match != all_entries_interesting) {
 			match = tree_entry_interesting(&entry, base, 0,
 						       &revs->diffopt.pathspec);
-			if (match < 0)
+			if (match == all_entries_not_interesting)
 				break;
-			if (match == 0)
+			if (match == entry_not_interesting)
 				continue;
 		}
 
diff --git a/tree-diff.c b/tree-diff.c
index 6782484489..7a51d091b5 100644
--- a/tree-diff.c
+++ b/tree-diff.c
@@ -64,14 +64,14 @@ static int compare_tree_entry(struct tree_desc *t1, struct tree_desc *t2,
 static void show_tree(struct diff_options *opt, const char *prefix,
 		      struct tree_desc *desc, struct strbuf *base)
 {
-	int match = 0;
+	enum interesting match = entry_not_interesting;
 	for (; desc->size; update_tree_entry(desc)) {
-		if (match != 2) {
+		if (match != all_entries_interesting) {
 			match = tree_entry_interesting(&desc->entry, base, 0,
 						       &opt->pathspec);
-			if (match < 0)
+			if (match == all_entries_not_interesting)
 				break;
-			if (match == 0)
+			if (match == entry_not_interesting)
 				continue;
 		}
 		show_entry(opt, prefix, desc, base);
@@ -114,12 +114,13 @@ static void show_entry(struct diff_options *opt, const char *prefix,
 }
 
 static void skip_uninteresting(struct tree_desc *t, struct strbuf *base,
-			       struct diff_options *opt, int *match)
+			       struct diff_options *opt,
+			       enum interesting *match)
 {
 	while (t->size) {
 		*match = tree_entry_interesting(&t->entry, base, 0, &opt->pathspec);
 		if (*match) {
-			if (*match < 0)
+			if (*match == all_entries_not_interesting)
 				t->size = 0;
 			break;
 		}
@@ -132,7 +133,8 @@ int diff_tree(struct tree_desc *t1, struct tree_desc *t2,
 {
 	struct strbuf base;
 	int baselen = strlen(base_str);
-	int t1_match = 0, t2_match = 0;
+	enum interesting t1_match = entry_not_interesting;
+	enum interesting t2_match = entry_not_interesting;
 
 	/* Enable recursion indefinitely */
 	opt->pathspec.recursive = DIFF_OPT_TST(opt, RECURSIVE);
diff --git a/tree-walk.c b/tree-walk.c
index cc2f14a0d6..4a03e9bd21 100644
--- a/tree-walk.c
+++ b/tree-walk.c
@@ -577,27 +577,23 @@ static int match_dir_prefix(const char *base,
  *
  * Pre-condition: either baselen == base_offset (i.e. empty path)
  * or base[baselen-1] == '/' (i.e. with trailing slash).
- *
- * Return:
- *  - 2 for "yes, and all subsequent entries will be"
- *  - 1 for yes
- *  - zero for no
- *  - negative for "no, and no subsequent entries will be either"
  */
-int tree_entry_interesting(const struct name_entry *entry,
-			   struct strbuf *base, int base_offset,
-			   const struct pathspec *ps)
+enum interesting tree_entry_interesting(const struct name_entry *entry,
+					struct strbuf *base, int base_offset,
+					const struct pathspec *ps)
 {
 	int i;
 	int pathlen, baselen = base->len - base_offset;
-	int never_interesting = ps->has_wildcard ? 0 : -1;
+	int never_interesting = ps->has_wildcard ?
+		entry_not_interesting : all_entries_not_interesting;
 
 	if (!ps->nr) {
 		if (!ps->recursive || ps->max_depth == -1)
-			return 2;
-		return !!within_depth(base->buf + base_offset, baselen,
-				      !!S_ISDIR(entry->mode),
-				      ps->max_depth);
+			return all_entries_interesting;
+		return within_depth(base->buf + base_offset, baselen,
+				    !!S_ISDIR(entry->mode),
+				    ps->max_depth) ?
+			entry_interesting : entry_not_interesting;
 	}
 
 	pathlen = tree_entry_len(entry);
@@ -614,12 +610,13 @@ int tree_entry_interesting(const struct name_entry *entry,
 				goto match_wildcards;
 
 			if (!ps->recursive || ps->max_depth == -1)
-				return 2;
+				return all_entries_interesting;
 
-			return !!within_depth(base_str + matchlen + 1,
-					      baselen - matchlen - 1,
-					      !!S_ISDIR(entry->mode),
-					      ps->max_depth);
+			return within_depth(base_str + matchlen + 1,
+					    baselen - matchlen - 1,
+					    !!S_ISDIR(entry->mode),
+					    ps->max_depth) ?
+				entry_interesting : entry_not_interesting;
 		}
 
 		/* Either there must be no base, or the base must match. */
@@ -627,18 +624,18 @@ int tree_entry_interesting(const struct name_entry *entry,
 			if (match_entry(entry, pathlen,
 					match + baselen, matchlen - baselen,
 					&never_interesting))
-				return 1;
+				return entry_interesting;
 
 			if (ps->items[i].use_wildcard) {
 				if (!fnmatch(match + baselen, entry->path, 0))
-					return 1;
+					return entry_interesting;
 
 				/*
 				 * Match all directories. We'll try to
 				 * match files later on.
 				 */
 				if (ps->recursive && S_ISDIR(entry->mode))
-					return 1;
+					return entry_interesting;
 			}
 
 			continue;
@@ -657,7 +654,7 @@ match_wildcards:
 
 		if (!fnmatch(match, base->buf + base_offset, 0)) {
 			strbuf_setlen(base, base_offset + baselen);
-			return 1;
+			return entry_interesting;
 		}
 		strbuf_setlen(base, base_offset + baselen);
 
@@ -666,7 +663,7 @@ match_wildcards:
 		 * later on.
 		 */
 		if (ps->recursive && S_ISDIR(entry->mode))
-			return 1;
+			return entry_interesting;
 	}
 	return never_interesting; /* No matches */
 }
diff --git a/tree-walk.h b/tree-walk.h
index 884d01ac33..2bf0db9814 100644
--- a/tree-walk.h
+++ b/tree-walk.h
@@ -61,6 +61,16 @@ static inline int traverse_path_len(const struct traverse_info *info, const stru
 	return info->pathlen + tree_entry_len(n);
 }
 
-extern int tree_entry_interesting(const struct name_entry *, struct strbuf *, int, const struct pathspec *ps);
+/* in general, positive means "kind of interesting" */
+enum interesting {
+	all_entries_not_interesting = -1, /* no, and no subsequent entries will be either */
+	entry_not_interesting = 0,
+	entry_interesting = 1,
+	all_entries_interesting = 2 /* yes, and all subsequent entries will be */
+};
+
+extern enum interesting tree_entry_interesting(const struct name_entry *,
+					       struct strbuf *, int,
+					       const struct pathspec *ps);
 
 #endif
diff --git a/tree.c b/tree.c
index e62219803b..676e9f710c 100644
--- a/tree.c
+++ b/tree.c
@@ -52,7 +52,8 @@ static int read_tree_1(struct tree *tree, struct strbuf *base,
 	struct tree_desc desc;
 	struct name_entry entry;
 	unsigned char sha1[20];
-	int len, retval = 0, oldlen = base->len;
+	int len, oldlen = base->len;
+	enum interesting retval = entry_not_interesting;
 
 	if (parse_tree(tree))
 		return -1;
@@ -60,11 +61,11 @@ static int read_tree_1(struct tree *tree, struct strbuf *base,
 	init_tree_desc(&desc, tree->buffer, tree->size);
 
 	while (tree_entry(&desc, &entry)) {
-		if (retval != 2) {
+		if (retval != all_entries_interesting) {
 			retval = tree_entry_interesting(&entry, base, 0, pathspec);
-			if (retval < 0)
+			if (retval == all_entries_not_interesting)
 				break;
-			if (retval == 0)
+			if (retval == entry_not_interesting)
 				continue;
 		}