diff --git a/base/renderprogs/builtin/lighting/ambient_lighting_IBL.ps.hlsl b/base/renderprogs/builtin/lighting/ambient_lighting_IBL.ps.hlsl
index d4108784..5fce3734 100644
--- a/base/renderprogs/builtin/lighting/ambient_lighting_IBL.ps.hlsl
+++ b/base/renderprogs/builtin/lighting/ambient_lighting_IBL.ps.hlsl
@@ -149,8 +149,12 @@ void main( PS_IN fragment, out PS_OUT result )
 	//float2 screenTexCoord = vposToScreenPosTexCoord( fragment.position.xy );
 	float2 screenTexCoord = fragment.position.xy * rpWindowCoord.xy;
 
-	float ao = tex2D( samp4, screenTexCoord ).r;
+	float ao = 1.0;
+
+#if !defined( USE_VULKAN )
+	ao = tex2D( samp4, screenTexCoord ).r;
 	//diffuseColor.rgb *= ao;
+#endif
 
 	// evaluate diffuse IBL
 
diff --git a/neo/renderer/RenderProgs_GLSL.cpp b/neo/renderer/RenderProgs_GLSL.cpp
index 7e155acf..a86e773e 100644
--- a/neo/renderer/RenderProgs_GLSL.cpp
+++ b/neo/renderer/RenderProgs_GLSL.cpp
@@ -516,6 +516,10 @@ idStr idRenderProgManager::StripDeadCode( const idStr& in, const char* name, con
 		src.AddDefine( "DEBUG_PBR" );
 	}
 
+#if defined( USE_VULKAN )
+	src.AddDefine( "USE_VULKAN" );
+#endif
+
 	// SMAA configuration
 	src.AddDefine( "SMAA_GLSL_3" );
 	src.AddDefine( "SMAA_RT_METRICS rpScreenCorrectionFactor " );