diff --git a/library/pkcs11_client.c b/library/pkcs11_client.c
index 79d6648..a3e387a 100644
--- a/library/pkcs11_client.c
+++ b/library/pkcs11_client.c
@@ -271,7 +271,7 @@
             attributes[0].type = CKA_MODULUS_BITS;
             attributes[0].pValue = &modulus_bits;
             attributes[0].ulValueLen = sizeof( modulus_bits );
-            rv = C_GetAttributeValue( hSession, hPrivateKey, attributes, 1 );
+            rv = C_GetAttributeValue( hSession, hPublicKey, attributes, 1 );
             if( rv != CKR_OK )
                 return( pkcs11_err_to_mbedtls_pk_err( rv ) );
             if( modulus_bits > (uint16_t)( -1 ) )