diff --git a/include/rcutils/testing/fault_injection.h b/include/rcutils/testing/fault_injection.h
index 6cb83fe2..34558320 100644
--- a/include/rcutils/testing/fault_injection.h
+++ b/include/rcutils/testing/fault_injection.h
@@ -59,7 +59,7 @@ rcutils_fault_injection_is_test_complete(void);
  */
 RCUTILS_PUBLIC
 void
-rcutils_fault_injection_set_count(int count);
+rcutils_fault_injection_set_count(int_least64_t count);
 
 /**
  * \brief Atomically get the fault injection counter value
diff --git a/src/testing/fault_injection.c b/src/testing/fault_injection.c
index 6f1c8547..3e0f64d5 100644
--- a/src/testing/fault_injection.c
+++ b/src/testing/fault_injection.c
@@ -18,7 +18,7 @@
 
 static atomic_int_least64_t g_rcutils_fault_injection_count = ATOMIC_VAR_INIT(-1);
 
-void rcutils_fault_injection_set_count(int count)
+void rcutils_fault_injection_set_count(int_least64_t count)
 {
   rcutils_atomic_store(&g_rcutils_fault_injection_count, count);
 }