diff --git a/library/constant_time_impl.h b/library/constant_time_impl.h
index 513f146..34b33b0 100644
--- a/library/constant_time_impl.h
+++ b/library/constant_time_impl.h
@@ -397,6 +397,17 @@
 
 #endif /* MBEDTLS_BIGNUM_C */
 
+static inline int mbedtls_ct_error_if(mbedtls_ct_condition_t condition, int if1, int if0)
+{
+    return -((int) mbedtls_ct_if(condition, (mbedtls_ct_uint_t) (-if1),
+                                 (mbedtls_ct_uint_t) (-if0)));
+}
+
+static inline int mbedtls_ct_error_if_else_0(mbedtls_ct_condition_t condition, int if1)
+{
+    return -((int) (condition & (-if1)));
+}
+
 static inline mbedtls_ct_condition_t mbedtls_ct_uint_eq(mbedtls_ct_uint_t x,
                                                         mbedtls_ct_uint_t y)
 {