diff --git a/c/omni_lock_time_lock.h b/c/omni_lock_time_lock.h
index 1b78789..357f83e 100644
--- a/c/omni_lock_time_lock.h
+++ b/c/omni_lock_time_lock.h
@@ -2,6 +2,7 @@
 #define OMNI_LOCK_TIME_LOCK_H_
 
 #include "ckb_utils.h"
+#define ERROR_INCORRECT_SINCE_FLAGS (-23)
 #define ERROR_INCORRECT_SINCE_VALUE (-24)
 
 /* check since,
@@ -27,7 +28,7 @@ int check_since(uint64_t since) {
     int comparable = 1;
     int cmp = ckb_since_cmp(since, input_since, &comparable);
     if (!comparable) {
-      return ERROR_INCORRECT_SINCE_VALUE;
+      return ERROR_INCORRECT_SINCE_FLAGS;
     }
     if (cmp == 1) {
       return ERROR_INCORRECT_SINCE_VALUE;
diff --git a/tests/omni_lock_rust/tests/test_multisig.rs b/tests/omni_lock_rust/tests/test_multisig.rs
index 378abeb..1041992 100644
--- a/tests/omni_lock_rust/tests/test_multisig.rs
+++ b/tests/omni_lock_rust/tests/test_multisig.rs
@@ -371,7 +371,7 @@ fn test_multisig_0_2_3_unlock_with_since_relative_not_comparable() {
     let mut verifier = verify_tx(resolved_tx, data_loader);
     verifier.set_debug_printer(debug_printer);
     let verify_result = verifier.verify(MAX_CYCLES);
-    assert_script_error(verify_result.unwrap_err(), ERROR_INCORRECT_SINCE_VALUE)
+    assert_script_error(verify_result.unwrap_err(), ERROR_INCORRECT_SINCE_FLAGS)
 }
 
 #[test]
@@ -390,7 +390,7 @@ fn test_multisig_0_2_3_unlock_with_since_flags() {
     let mut verifier = verify_tx(resolved_tx, data_loader);
     verifier.set_debug_printer(debug_printer);
     let verify_result = verifier.verify(MAX_CYCLES);
-    assert_script_error(verify_result.unwrap_err(), ERROR_INCORRECT_SINCE_VALUE)
+    assert_script_error(verify_result.unwrap_err(), ERROR_INCORRECT_SINCE_FLAGS)
 }
 
 #[test]
@@ -434,7 +434,7 @@ fn test_multisig_0_2_3_unlock_with_since_epoch() {
     let mut verifier = verify_tx(resolved_tx, data_loader);
     verifier.set_debug_printer(debug_printer);
     let verify_result = verifier.verify(MAX_CYCLES);
-    assert_script_error(verify_result.unwrap_err(), ERROR_INCORRECT_SINCE_VALUE)
+    assert_script_error(verify_result.unwrap_err(), ERROR_INCORRECT_SINCE_FLAGS)
 }
 
 #[test]