diff --git a/src/mbuf.c b/src/mbuf.c
index d77dd7b..390630f 100644
--- a/src/mbuf.c
+++ b/src/mbuf.c
@@ -127,10 +127,10 @@ int uc_mbuf_extend_tailroom(struct MBuf *mbuf, uint32_t len)
     uint32_t data_len;
     uint32_t tailroom_len;
     uint8_t *new_data;
-    uint32_t p1_off;
-    uint32_t p2_off;
-    uint32_t p3_off;
-    uint32_t p4_off;
+    uint32_t p1_off = 0;
+    uint32_t p2_off = 0;
+    uint32_t p3_off = 0;
+    uint32_t p4_off = 0;
 
     if ((mbuf->flags & (UC_MBUF_FL_MALLOC | UC_MBUF_FL_MALLOC_BUF)) == 0) {
         return -1;