diff --git a/include/zmalloc.h b/include/zmalloc.h
index 76a3a7f..383f377 100644
--- a/include/zmalloc.h
+++ b/include/zmalloc.h
@@ -70,6 +70,7 @@ void *zcalloc(size_t size);
 void *zrealloc(void *ptr, size_t size);
 void zfree(void *ptr);
 char *zstrdup(const char *s);
+char *zstrndup(const char *s, size_t n);
 size_t zmalloc_used_memory(void);
 void zmalloc_enable_thread_safeness(void);
 void zmalloc_set_oom_handler(void (*oom_handler)(size_t));
diff --git a/src/edge.c b/src/edge.c
index a179f77..f50dc1e 100644
--- a/src/edge.c
+++ b/src/edge.c
@@ -55,7 +55,7 @@ node * r3_edge_branch(edge *e, int dl) {
     // the suffix edge of the leaf
     new_child = r3_tree_create(3);
     s1_len = e->pattern_len - dl;
-    e1 = r3_edge_create(strndup(s1, s1_len), s1_len, new_child);
+    e1 = r3_edge_create(zstrndup(s1, s1_len), s1_len, new_child);
 
     // Migrate the child edges to the new edge we just created.
     for ( int i = 0 ; i < tmp_edge_len ; i++ ) {
diff --git a/src/node.c b/src/node.c
index b2d339c..a9e0a76 100644
--- a/src/node.c
+++ b/src/node.c
@@ -306,7 +306,7 @@ node * r3_tree_matchl(const node * n, char * path, int path_len, match_entry * e
 
                 if (entry && e->has_slug) {
                     // append captured token to entry
-                    str_array_append(entry->vars , strndup(substring_start, substring_length));
+                    str_array_append(entry->vars , zstrndup(substring_start, substring_length));
                 }
                 if (restlen == 0 ) {
                     return e->child && e->child->endpoint > 0 ? e->child : NULL;
@@ -459,14 +459,14 @@ node * r3_tree_insert_pathl_(node *tree, char *path, int path_len, route * route
 
             // insert the first one edge, and break at "p"
             node * child = r3_tree_create(3);
-            r3_node_add_child(n, strndup(path, (int)(p - path)), child);
+            r3_node_add_child(n, zstrndup(path, (int)(p - path)), child);
             child->endpoint = 0;
 
             // and insert the rest part to the child
             return r3_tree_insert_pathl_(child, p, path_len - (int)(p - path),  route, data);
         } else {
             node * child = r3_tree_create(3);
-            r3_node_add_child(n, strndup(path, path_len) , child);
+            r3_node_add_child(n, zstrndup(path, path_len) , child);
             // info("edge not found, insert one: %s\n", path);
             child->data = data;
             child->endpoint++;
diff --git a/src/str.c b/src/str.c
index 564c754..c83cd92 100644
--- a/src/str.c
+++ b/src/str.c
@@ -204,7 +204,7 @@ char *zstrdup(const char *s) {
 #endif
 
 #ifndef HAVE_STRNDUP
-char *strndup(const char *s, int n) {
+char *zstrndup(const char *s, int n) {
     char *out;
     int count = 0;
     while( count < n && s[count] )
diff --git a/src/zmalloc.c b/src/zmalloc.c
index d0cf726..72447d8 100644
--- a/src/zmalloc.c
+++ b/src/zmalloc.c
@@ -215,6 +215,22 @@ char *zstrdup(const char *s) {
     return p;
 }
 
+char * zstrndup (const char *s, size_t n)
+{
+  char *result;
+  size_t len = strlen (s);
+
+  if (n < len)
+    len = n;
+
+  result = (char *) zmalloc (len + 1);
+  if (!result)
+    return 0;
+
+  result[len] = '\0';
+  return (char *) memcpy (result, s, len);
+}
+
 size_t zmalloc_used_memory(void) {
     size_t um;