diff --git a/library/cipher.c b/library/cipher.c
index da55206..d7acf34 100644
--- a/library/cipher.c
+++ b/library/cipher.c
@@ -242,6 +242,9 @@
     else if( NULL == iv && iv_len != 0  )
         return( MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA );
 
+    if( NULL == iv && iv_len == 0 )
+        ctx->iv_size = 0;
+
     /* avoid buffer overflow in ctx->iv */
     if( iv_len > MBEDTLS_MAX_IV_LENGTH )
         return( MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE );
@@ -269,7 +272,7 @@
     }
 #endif
 
-    if ( actual_iv_size )
+    if ( actual_iv_size != 0 )
     {
         memcpy( ctx->iv, iv, actual_iv_size );
         ctx->iv_size = actual_iv_size;