diff --git a/libraries/AP_HAL_SITL/Util.cpp b/libraries/AP_HAL_SITL/Util.cpp
index ce51bd8fd3..1805e21720 100644
--- a/libraries/AP_HAL_SITL/Util.cpp
+++ b/libraries/AP_HAL_SITL/Util.cpp
@@ -85,7 +85,7 @@ bool HALSITL::Util::get_system_id(char buf[50])
     return get_system_id_unformatted((uint8_t *)buf, len);
 }
 
-#ifdef ENABLE_HEAP
+#if ENABLE_HEAP
 void *HALSITL::Util::allocate_heap_memory(size_t size)
 {
     struct heap *new_heap = (struct heap*)malloc(sizeof(struct heap));
diff --git a/libraries/AP_HAL_SITL/Util.h b/libraries/AP_HAL_SITL/Util.h
index cbfbeda556..ac73c6a365 100644
--- a/libraries/AP_HAL_SITL/Util.h
+++ b/libraries/AP_HAL_SITL/Util.h
@@ -43,7 +43,7 @@ public:
     bool get_system_id_unformatted(uint8_t buf[], uint8_t &len) override;
     void dump_stack_trace();
 
-#ifdef ENABLE_HEAP
+#if ENABLE_HEAP
     // heap functions, note that a heap once alloc'd cannot be dealloc'd
     void *allocate_heap_memory(size_t size) override;
     void *heap_realloc(void *heap, void *ptr, size_t old_size, size_t new_size) override;
@@ -90,7 +90,7 @@ private:
     static ToneAlarm_SF _toneAlarm;
 #endif
 
-#ifdef ENABLE_HEAP
+#if ENABLE_HEAP
     struct heap_allocation_header {
         size_t allocation_size; // size of allocated block, not including this header
     };