diff --git a/perf-event-open-sys/src/functions.rs b/perf-event-open-sys/src/functions.rs
index ff556c0..2cd679c 100644
--- a/perf-event-open-sys/src/functions.rs
+++ b/perf-event-open-sys/src/functions.rs
@@ -86,7 +86,7 @@ pub mod ioctls {
         { DISABLE, DISABLE, c_uint }
         { REFRESH, REFRESH, c_int }
         { RESET, RESET, c_uint }
-        { PERIOD, PERIOD, u64 }
+        { PERIOD, PERIOD, *const u64 }
         { SET_OUTPUT, SET_OUTPUT, c_int }
         { SET_FILTER, SET_FILTER, *mut c_char }
         { ID, ID, *mut u64 }
diff --git a/perf-event/src/hooks.rs b/perf-event/src/hooks.rs
index 591b6c1..d7cac98 100644
--- a/perf-event/src/hooks.rs
+++ b/perf-event/src/hooks.rs
@@ -118,7 +118,7 @@ macro_rules! define_ioctls {
         $expand ! { DISABLE, perf_event_ioctls_DISABLE, c_uint }
         $expand ! { REFRESH, perf_event_ioctls_REFRESH, c_int }
         $expand ! { RESET, perf_event_ioctls_RESET, c_uint }
-        $expand ! { PERIOD, perf_event_ioctls_PERIOD, u64 }
+        $expand ! { PERIOD, perf_event_ioctls_PERIOD, *const u64 }
         $expand ! { SET_OUTPUT, perf_event_ioctls_SET_OUTPUT, c_int }
         $expand ! { SET_FILTER, perf_event_ioctls_SET_FILTER, *mut c_char }
         $expand ! { ID, perf_event_ioctls_ID, *mut u64 }