diff --git a/src/SharedMemoryAccess.cpp b/src/SharedMemoryAccess.cpp
index bdbd9b6..e410c3f 100644
--- a/src/SharedMemoryAccess.cpp
+++ b/src/SharedMemoryAccess.cpp
@@ -15,10 +15,10 @@
 #include "SharedMemoryAccess.h"  /* header is important for the shmID. name could be different. maybe not needed cause: (shmget(memory_access_key, NULL, 0)) */
 #include "internal.h"
 
-#define PERM 0666      /* access rights */
-#define LOCK       (-1)
-#define UNLOCK      (1)
-#define SEM_KEY  (123458L)
+constexpr int PERM = 0666;      /* access rights */
+constexpr int LOCK = -1;
+constexpr int UNLOCK = 1;
+constexpr int SEM_KEY = 123458L;
 
 //int memoryAccessKey; /* var type is int. but could be another type. */ //TODO: look after type in sharedmemory group
 int semId;