diff --git a/library/x509_crt.c b/library/x509_crt.c
index 7dae26e..97e1d72 100644
--- a/library/x509_crt.c
+++ b/library/x509_crt.c
@@ -393,7 +393,7 @@
             return( 0 );
         }
 
-        return( ret );
+        return( MBEDTLS_ERR_X509_INVALID_FORMAT + ret );
     }
 
     end = *p + len;
@@ -460,7 +460,7 @@
         if( ret == MBEDTLS_ERR_ASN1_UNEXPECTED_TAG )
             return( 0 );
 
-        return( ret );
+        return( MBEDTLS_ERR_X509_INVALID_FORMAT + ret );
     }
 
     uid->p = *p;
@@ -703,12 +703,7 @@
         return( 0 );
 
     if( ( ret = mbedtls_x509_get_ext( p, end, &crt->v3_ext, 3 ) ) != 0 )
-    {
-        if( ret == MBEDTLS_ERR_ASN1_UNEXPECTED_TAG )
-            return( 0 );
-
         return( ret );
-    }
 
     end = crt->v3_ext.p + crt->v3_ext.len;
     while( *p < end )