diff --git a/library/rsa.c b/library/rsa.c
index a387d09..ea88871 100644
--- a/library/rsa.c
+++ b/library/rsa.c
@@ -1517,9 +1517,8 @@
     if( ret != 0 )
         goto cleanup;
 
-    ret = mbedtls_cf_rsaes_pkcs1_v15_unpadding( mode, ilen, olen, output,
-                                                output_max_len,
-                                                (unsigned char *) &buf );
+    ret = mbedtls_cf_rsaes_pkcs1_v15_unpadding( mode, buf, ilen,
+                                                output, output_max_len, olen );
 
 cleanup:
     mbedtls_platform_zeroize( buf, sizeof( buf ) );