diff --git a/certora/mutations/034_nextPeriod_advancement_failure.patch b/certora/mutations/034_nextPeriod_advancement_failure.patch
new file mode 100644
index 0000000..d2b607b
--- /dev/null
+++ b/certora/mutations/034_nextPeriod_advancement_failure.patch
@@ -0,0 +1,13 @@
+diff --git a/contracts/Periods.sol b/contracts/Periods.sol
+index 189fb02..817d09c 100644
+--- a/contracts/Periods.sol
++++ b/contracts/Periods.sol
+@@ -29,7 +29,7 @@ contract Periods {
+   }
+ 
+   function _nextPeriod(Period period) internal pure returns (Period) {
+-    return Period.wrap(Period.unwrap(period) + 1);
++    return Period.wrap(Period.unwrap(period));
+   }
+ 
+   function _periodStart(Period period) internal view returns (Timestamp) {