diff --git a/src/server.h b/src/server.h
index 047834ae2..9ad1aab8d 100644
--- a/src/server.h
+++ b/src/server.h
@@ -3384,7 +3384,7 @@ int zslLexValueGteMin(sds value, zlexrangespec *spec);
 int zslLexValueLteMax(sds value, zlexrangespec *spec);
 
 /* Core functions */
-int getMaxmemoryState(size_t *total, size_t *logical, size_t *tofree, float *level, EvictReason *reason=NULL, bool fQuickCycle=false, bool fPreSnapshot=false);
+int getMaxmemoryState(size_t *total, size_t *logical, size_t *tofree, float *level, EvictReason *reason=nullptr, bool fQuickCycle=false, bool fPreSnapshot=false);
 size_t freeMemoryGetNotCountedMemory();
 int overMaxmemoryAfterAlloc(size_t moremem);
 int processCommand(client *c, int callFlags);