diff --git a/proprietary/wvm/WVMExtractorImpl.cpp b/proprietary/wvm/WVMExtractorImpl.cpp
index c5092839..967adb03 100644
--- a/proprietary/wvm/WVMExtractorImpl.cpp
+++ b/proprietary/wvm/WVMExtractorImpl.cpp
@@ -41,7 +41,7 @@ static int _cb2(char *in, char *out, int length, char *iv)
 
     if (sDrmManagerClient != NULL) {
         DrmBuffer encryptedDrmBuffer(in, length);
-        DrmBuffer ivBuffer(iv, length);
+        DrmBuffer ivBuffer(iv, (iv? AES_BLOCK_SIZE: 0));
 
         DrmBuffer decryptedDrmBuffer(out, length);
         DrmBuffer *decryptedDrmBufferPtr = &decryptedDrmBuffer;