diff --git a/library/cipher.c b/library/cipher.c
index bd39e4f..b410182 100644
--- a/library/cipher.c
+++ b/library/cipher.c
@@ -282,6 +282,10 @@
 
     *olen = 0;
     block_size = mbedtls_cipher_get_block_size( ctx );
+    if ( 0 == block_size )
+    {
+        return( MBEDTLS_ERR_CIPHER_INVALID_CONTEXT );
+    }
 
     if( ctx->cipher_info->mode == MBEDTLS_MODE_ECB )
     {
@@ -308,11 +312,6 @@
     }
 #endif
 
-    if ( 0 == block_size )
-    {
-        return MBEDTLS_ERR_CIPHER_INVALID_CONTEXT;
-    }
-
     if( input == output &&
        ( ctx->unprocessed_len != 0 || ilen % block_size ) )
     {
@@ -371,11 +370,6 @@
          */
         if( 0 != ilen )
         {
-            if( 0 == block_size )
-            {
-                return MBEDTLS_ERR_CIPHER_INVALID_CONTEXT;
-            }
-
             /* Encryption: only cache partial blocks
              * Decryption w/ padding: always keep at least one whole block
              * Decryption w/o padding: only cache partial blocks