diff --git a/src/crypto.c b/src/crypto.c
index e60b533..7519849 100644
--- a/src/crypto.c
+++ b/src/crypto.c
@@ -684,7 +684,7 @@ static void* sqlite3Codec(void *iCtx, void *data, Pgno pgno, int mode) {
 
       rc = sqlcipher_page_cipher(ctx, cctx, pgno, CIPHER_DECRYPT, page_sz - offset, pData + offset, (unsigned char*)buffer + offset);
       if(rc != SQLITE_OK) { /* clear results of failed cipher operation and set error */
-        sqlcipher_memset(buffer+offset, 0, page_sz-offset);
+        sqlcipher_memset((unsigned char*) buffer+offset, 0, page_sz-offset);
         sqlcipher_codec_ctx_set_error(ctx, rc);
       }
       memcpy(pData, buffer, page_sz); /* copy buffer data back to pData and return */
@@ -706,7 +706,7 @@ static void* sqlite3Codec(void *iCtx, void *data, Pgno pgno, int mode) {
       }
       rc = sqlcipher_page_cipher(ctx, cctx, pgno, CIPHER_ENCRYPT, page_sz - offset, pData + offset, (unsigned char*)buffer + offset);
       if(rc != SQLITE_OK) { /* clear results of failed cipher operation and set error */
-        sqlcipher_memset(buffer+offset, 0, page_sz-offset);
+        sqlcipher_memset((unsigned char*)buffer+offset, 0, page_sz-offset);
         sqlcipher_codec_ctx_set_error(ctx, rc);
       }
       return buffer; /* return persistent buffer data, pData remains intact */