diff --git a/src/SourceEngine/Main.ts b/src/SourceEngine/Main.ts
index 7e978a469..840bec8cc 100644
--- a/src/SourceEngine/Main.ts
+++ b/src/SourceEngine/Main.ts
@@ -762,8 +762,10 @@ export class BSPRenderer {
 
                 for (const faceIdx of this.liveFaceSet.values()) {
                     const lightmapUpdater = this.lightmapUpdaters[faceIdx];
-                    if (lightmapUpdater !== null && lightmapUpdater.checkDirty(renderContext))
+                    if (lightmapUpdater !== null) {
+                        lightmapUpdater.update(renderContext);
                         lightmapUpdater.buildLightmap(renderContext, this.startLightmapPageIndex);
+                    }
 
                     const faceInfo = this.bsp.faceInfos[faceIdx];
                     if (faceInfo.surfaceIndex >= 0)
@@ -798,8 +800,10 @@ export class BSPRenderer {
                         const faceIdx = surface.surface.faceList[k];
                         
                         const lightmapUpdater = this.lightmapUpdaters[faceIdx];
-                        if (lightmapUpdater !== null && lightmapUpdater.checkDirty(renderContext))
+                        if (lightmapUpdater !== null) {
+                            lightmapUpdater.update(renderContext);
                             lightmapUpdater.buildLightmap(renderContext, this.startLightmapPageIndex);
+                        }
                     }
                 }
 
diff --git a/src/SourceEngine/Materials/Lightmap.ts b/src/SourceEngine/Materials/Lightmap.ts
index 2cc61a9c3..368451dc8 100644
--- a/src/SourceEngine/Materials/Lightmap.ts
+++ b/src/SourceEngine/Materials/Lightmap.ts
@@ -212,11 +212,16 @@ function lightmapPackRuntimeBumpmap(dstPage: LightmapPage, location: Readonly<Fa
     }
 }
 
+const enum FaceLightmapUpdaterState {
+    NotReady,
+    NeedsUpload,
+    Idle,
+}
 
 export class FaceLightmapUpdater {
     // The styles that we built our lightmaps for.
     private lightmapStyleIntensities: number[];
-    private initialized: boolean = false;
+    private state = FaceLightmapUpdaterState.NotReady;
     private wantsLightmap: boolean = false;
     private wantsBumpmap: boolean = false;
 
@@ -225,13 +230,13 @@ export class FaceLightmapUpdater {
     }
 
     public setMaterial(materialInstance: BaseMaterial): void {
-        assert(!this.initialized);
-        this.initialized = true;
+        assert(this.state === FaceLightmapUpdaterState.NotReady);
+        this.state = FaceLightmapUpdaterState.NeedsUpload;
         this.wantsLightmap = materialInstance.wantsLightmap;
         this.wantsBumpmap = materialInstance.wantsBumpmappedLightmap;
     }
 
-    public checkDirty(renderContext: SourceRenderContext): boolean {
+    private checkDirty(renderContext: SourceRenderContext): boolean {
         const worldLightingState = renderContext.worldLightingState;
 
         if (!this.wantsLightmap)
@@ -246,8 +251,13 @@ export class FaceLightmapUpdater {
         return false;
     }
 
+    public update(renderContext: SourceRenderContext): void {
+        if (this.state === FaceLightmapUpdaterState.Idle && this.checkDirty(renderContext))
+            this.state = FaceLightmapUpdaterState.NeedsUpload;
+    }
+
     public buildLightmap(renderContext: SourceRenderContext, pageOffset: number): void {
-        if (!this.initialized)
+        if (this.state !== FaceLightmapUpdaterState.NeedsUpload)
             return;
 
         const worldLightingState = renderContext.worldLightingState;
@@ -293,5 +303,6 @@ export class FaceLightmapUpdater {
 
         dstPage.uploadDirty = true;
         renderContext.debugStatistics.lightmapsBuilt++;
+        this.state = FaceLightmapUpdaterState.Idle;
     }
 }
diff --git a/src/SourceEngine/Materials/Material_Generic.ts b/src/SourceEngine/Materials/Material_Generic.ts
index c65c0ff1d..3c2179a52 100644
--- a/src/SourceEngine/Materials/Material_Generic.ts
+++ b/src/SourceEngine/Materials/Material_Generic.ts
@@ -1117,13 +1117,13 @@ export class Material_Generic extends BaseMaterial {
         super.initParameters();
 
         const shaderTypeStr = this.vmt._Root.toLowerCase();
-        if (shaderTypeStr === 'lightmappedgeneric')
+        if (shaderTypeStr === 'lightmappedgeneric' || shaderTypeStr === 'sdk_lightmappedgeneric')
             this.shaderType = GenericShaderType.LightmappedGeneric;
         else if (shaderTypeStr === 'vertexlitgeneric')
             this.shaderType = GenericShaderType.VertexLitGeneric;
         else if (shaderTypeStr === 'unlitgeneric')
             this.shaderType = GenericShaderType.UnlitGeneric;
-        else if (shaderTypeStr === 'worldvertextransition')
+        else if (shaderTypeStr === 'worldvertextransition' || shaderTypeStr === 'sdk_worldvertextransition')
             this.shaderType = GenericShaderType.WorldVertexTransition;
         else if (shaderTypeStr === 'black')
             this.shaderType = GenericShaderType.Black;