diff --git a/src/Core/Resource/CAudioMacro.h b/src/Core/Resource/CAudioMacro.h
index b09f0fcc..e1bd043e 100644
--- a/src/Core/Resource/CAudioMacro.h
+++ b/src/Core/Resource/CAudioMacro.h
@@ -12,7 +12,7 @@ class CAudioMacro : public CResource
     std::vector<CAssetID> mSamples;
 
 public:
-    CAudioMacro(CResourceEntry *pEntry = 0)
+    explicit CAudioMacro(CResourceEntry *pEntry = nullptr)
         : CResource(pEntry)
     {}