diff --git a/abspath.c b/abspath.c
index e390994abf..9c908e395b 100644
--- a/abspath.c
+++ b/abspath.c
@@ -215,23 +215,25 @@ const char *absolute_path(const char *path)
  */
 const char *prefix_filename(const char *pfx, int pfx_len, const char *arg)
 {
-	static char path[PATH_MAX];
+	static struct strbuf path = STRBUF_INIT;
 #ifndef GIT_WINDOWS_NATIVE
 	if (!pfx_len || is_absolute_path(arg))
 		return arg;
-	memcpy(path, pfx, pfx_len);
-	strcpy(path + pfx_len, arg);
+	strbuf_reset(&path);
+	strbuf_add(&path, pfx, pfx_len);
+	strbuf_addstr(&path, arg);
 #else
 	char *p;
 	/* don't add prefix to absolute paths, but still replace '\' by '/' */
+	strbuf_reset(&path);
 	if (is_absolute_path(arg))
 		pfx_len = 0;
 	else if (pfx_len)
-		memcpy(path, pfx, pfx_len);
-	strcpy(path + pfx_len, arg);
-	for (p = path + pfx_len; *p; p++)
+		strbuf_add(&path, pfx, pfx_len);
+	strbuf_addstr(&path, arg);
+	for (p = path.buf + pfx_len; *p; p++)
 		if (*p == '\\')
 			*p = '/';
 #endif
-	return path;
+	return path.buf;
 }
diff --git a/diffcore-order.c b/diffcore-order.c
index 23e93852d8..50c089bb2b 100644
--- a/diffcore-order.c
+++ b/diffcore-order.c
@@ -73,15 +73,16 @@ struct pair_order {
 static int match_order(const char *path)
 {
 	int i;
-	char p[PATH_MAX];
+	static struct strbuf p = STRBUF_INIT;
 
 	for (i = 0; i < order_cnt; i++) {
-		strcpy(p, path);
-		while (p[0]) {
+		strbuf_reset(&p);
+		strbuf_addstr(&p, path);
+		while (p.buf[0]) {
 			char *cp;
-			if (!fnmatch(order[i], p, 0))
+			if (!fnmatch(order[i], p.buf, 0))
 				return i;
-			cp = strrchr(p, '/');
+			cp = strrchr(p.buf, '/');
 			if (!cp)
 				break;
 			*cp = 0;
diff --git a/unpack-trees.c b/unpack-trees.c
index ad3e9a04fe..164354dad7 100644
--- a/unpack-trees.c
+++ b/unpack-trees.c
@@ -830,23 +830,24 @@ static int unpack_callback(int n, unsigned long mask, unsigned long dirmask, str
 }
 
 static int clear_ce_flags_1(struct cache_entry **cache, int nr,
-			    char *prefix, int prefix_len,
+			    struct strbuf *prefix,
 			    int select_mask, int clear_mask,
 			    struct exclude_list *el, int defval);
 
 /* Whole directory matching */
 static int clear_ce_flags_dir(struct cache_entry **cache, int nr,
-			      char *prefix, int prefix_len,
+			      struct strbuf *prefix,
 			      char *basename,
 			      int select_mask, int clear_mask,
 			      struct exclude_list *el, int defval)
 {
 	struct cache_entry **cache_end;
 	int dtype = DT_DIR;
-	int ret = is_excluded_from_list(prefix, prefix_len,
+	int ret = is_excluded_from_list(prefix->buf, prefix->len,
 					basename, &dtype, el);
+	int rc;
 
-	prefix[prefix_len++] = '/';
+	strbuf_addch(prefix, '/');
 
 	/* If undecided, use matching result of parent dir in defval */
 	if (ret < 0)
@@ -854,7 +855,7 @@ static int clear_ce_flags_dir(struct cache_entry **cache, int nr,
 
 	for (cache_end = cache; cache_end != cache + nr; cache_end++) {
 		struct cache_entry *ce = *cache_end;
-		if (strncmp(ce->name, prefix, prefix_len))
+		if (strncmp(ce->name, prefix->buf, prefix->len))
 			break;
 	}
 
@@ -865,10 +866,12 @@ static int clear_ce_flags_dir(struct cache_entry **cache, int nr,
 	 * calling clear_ce_flags_1(). That function will call
 	 * the expensive is_excluded_from_list() on every entry.
 	 */
-	return clear_ce_flags_1(cache, cache_end - cache,
-				prefix, prefix_len,
-				select_mask, clear_mask,
-				el, ret);
+	rc = clear_ce_flags_1(cache, cache_end - cache,
+			      prefix,
+			      select_mask, clear_mask,
+			      el, ret);
+	strbuf_setlen(prefix, prefix->len - 1);
+	return rc;
 }
 
 /*
@@ -887,7 +890,7 @@ static int clear_ce_flags_dir(struct cache_entry **cache, int nr,
  * Top level path has prefix_len zero.
  */
 static int clear_ce_flags_1(struct cache_entry **cache, int nr,
-			    char *prefix, int prefix_len,
+			    struct strbuf *prefix,
 			    int select_mask, int clear_mask,
 			    struct exclude_list *el, int defval)
 {
@@ -907,10 +910,10 @@ static int clear_ce_flags_1(struct cache_entry **cache, int nr,
 			continue;
 		}
 
-		if (prefix_len && strncmp(ce->name, prefix, prefix_len))
+		if (prefix->len && strncmp(ce->name, prefix->buf, prefix->len))
 			break;
 
-		name = ce->name + prefix_len;
+		name = ce->name + prefix->len;
 		slash = strchr(name, '/');
 
 		/* If it's a directory, try whole directory match first */
@@ -918,29 +921,26 @@ static int clear_ce_flags_1(struct cache_entry **cache, int nr,
 			int processed;
 
 			len = slash - name;
-			memcpy(prefix + prefix_len, name, len);
+			strbuf_add(prefix, name, len);
 
-			/*
-			 * terminate the string (no trailing slash),
-			 * clear_c_f_dir needs it
-			 */
-			prefix[prefix_len + len] = '\0';
 			processed = clear_ce_flags_dir(cache, cache_end - cache,
-						       prefix, prefix_len + len,
-						       prefix + prefix_len,
+						       prefix,
+						       prefix->buf + prefix->len - len,
 						       select_mask, clear_mask,
 						       el, defval);
 
 			/* clear_c_f_dir eats a whole dir already? */
 			if (processed) {
 				cache += processed;
+				strbuf_setlen(prefix, prefix->len - len);
 				continue;
 			}
 
-			prefix[prefix_len + len++] = '/';
+			strbuf_addch(prefix, '/');
 			cache += clear_ce_flags_1(cache, cache_end - cache,
-						  prefix, prefix_len + len,
+						  prefix,
 						  select_mask, clear_mask, el, defval);
+			strbuf_setlen(prefix, prefix->len - len - 1);
 			continue;
 		}
 
@@ -961,9 +961,12 @@ static int clear_ce_flags(struct cache_entry **cache, int nr,
 			    int select_mask, int clear_mask,
 			    struct exclude_list *el)
 {
-	char prefix[PATH_MAX];
+	static struct strbuf prefix = STRBUF_INIT;
+
+	strbuf_reset(&prefix);
+
 	return clear_ce_flags_1(cache, nr,
-				prefix, 0,
+				&prefix,
 				select_mask, clear_mask,
 				el, 0);
 }