diff --git a/neo/renderer/RenderBackend.cpp b/neo/renderer/RenderBackend.cpp
index 05166704..0d83e31a 100644
--- a/neo/renderer/RenderBackend.cpp
+++ b/neo/renderer/RenderBackend.cpp
@@ -1203,8 +1203,13 @@ const int INTERACTION_TEXUNIT_PROJECTION	= 4;
 const int INTERACTION_TEXUNIT_SHADOWMAPS	= 5;
 const int INTERACTION_TEXUNIT_JITTER		= 6;
 
+#if defined( USE_VULKAN )
+const int INTERACTION_TEXUNIT_AMBIENT_CUBE1 = 3;
+const int INTERACTION_TEXUNIT_SPECULAR_CUBE1 = 4;
+#else
 const int INTERACTION_TEXUNIT_AMBIENT_CUBE1 = 7;
 const int INTERACTION_TEXUNIT_SPECULAR_CUBE1 = 8;
+#endif
 
 /*
 ==================