diff --git a/src/block_common.c b/src/block_common.c
index 169200a6..c6da1f85 100644
--- a/src/block_common.c
+++ b/src/block_common.c
@@ -106,7 +106,7 @@ EXPORT_SYM int CIPHER_START_OPERATION(const uint8_t key[], size_t key_len, CIPHE
     if ((key == NULL) || (pResult == NULL))
         return ERR_NULL;

-    *pResult = calloc(1, sizeof(CIPHER_STATE_TYPE));
+    *pResult = (CIPHER_STATE_TYPE *) calloc(1, sizeof(CIPHER_STATE_TYPE));
     if (NULL == *pResult)
         return ERR_MEMORY;