diff --git a/src/ZoneWriting/Zone/Stream/IZoneOutputStream.h b/src/ZoneWriting/Zone/Stream/IZoneOutputStream.h
index 71a752e0..e1244a4c 100644
--- a/src/ZoneWriting/Zone/Stream/IZoneOutputStream.h
+++ b/src/ZoneWriting/Zone/Stream/IZoneOutputStream.h
@@ -9,8 +9,8 @@
 class IZoneOutputStream : public IZoneStream
 {
 public:
-    static constexpr void* PTR_FOLLOWING = reinterpret_cast<void*>(-1);
-    static constexpr void* PTR_INSERT = reinterpret_cast<void*>(-2);
+    inline static void* const PTR_FOLLOWING = reinterpret_cast<void*>(-1);
+    inline static void* const PTR_INSERT = reinterpret_cast<void*>(-2);
 
     virtual void Align(int alignTo) = 0;