diff --git a/core/include/oneway_malloc.h b/core/include/oneway_malloc.h
index 4e64615ef6..76946dfd04 100644
--- a/core/include/oneway_malloc.h
+++ b/core/include/oneway_malloc.h
@@ -13,6 +13,7 @@
 
 void *_malloc(size_t size);
 void *_realloc(void *ptr, size_t size);
+void *_calloc(int size, size_t cnt);
 void _free(void *ptr);
 
 /** @} */
diff --git a/core/oneway_malloc.c b/core/oneway_malloc.c
index 4c3e9eba17..c8e8fd5c2e 100644
--- a/core/oneway_malloc.c
+++ b/core/oneway_malloc.c
@@ -47,6 +47,15 @@ void *_realloc(void *ptr, size_t size)
     return newptr;
 }
 
+void *_calloc(int size, size_t cnt)
+{
+    void *mem = _malloc(size * cnt);
+    if (mem) {
+        memset(mem, 0, size * cnt);
+    }
+    return mem;
+}
+
 void _free(void *ptr)
 {
     /* who cares about pointers? */