diff --git a/library/rsa.c b/library/rsa.c
index ab0bd67..1909744 100644
--- a/library/rsa.c
+++ b/library/rsa.c
@@ -2259,7 +2259,7 @@
     if( verbose != 0 )
         mbedtls_printf( "  PKCS#1 data sign  : " );
 
-    if( mbedtls_sha1_ext( rsa_plaintext, PT_LEN, sha1sum ) != 0 )
+    if( mbedtls_sha1_ret( rsa_plaintext, PT_LEN, sha1sum ) != 0 )
     {
         if( verbose != 0 )
             mbedtls_printf( "failed\n" );