diff --git a/compiler/src/prog8/optimizer/CallGraph.kt b/compiler/src/prog8/optimizer/CallGraph.kt
index c2a12d9ae..715cbc303 100644
--- a/compiler/src/prog8/optimizer/CallGraph.kt
+++ b/compiler/src/prog8/optimizer/CallGraph.kt
@@ -104,7 +104,12 @@ class CallGraph(private val program: Program): IAstVisitor {
     }
 
     override fun visit(subroutine: Subroutine) {
-        if((subroutine.name=="start" && subroutine.definingScope().name=="main")
+        val alwaysKeepSubroutines = setOf(
+                Pair("main", "start"),
+                Pair("irq", "irq")
+        )
+
+        if(Pair(subroutine.definingScope().name, subroutine.name) in alwaysKeepSubroutines
                 || subroutine.name== initvarsSubName || subroutine.definingModule().isLibraryModule) {
             // make sure the entrypoint is mentioned in the used symbols
             addNodeAndParentScopes(subroutine)
diff --git a/examples/rasterbars.p8 b/examples/rasterbars.p8
index 94a5c0ffe..503082a6e 100644
--- a/examples/rasterbars.p8
+++ b/examples/rasterbars.p8
@@ -5,10 +5,11 @@
 ~ main {
 
     sub start() {
-        c64.SCROLY &= %11101111           ; blank the screen
-        c64utils.set_rasterirq_excl(40)
+        c64.SCROLY &= %11101111             ; blank the screen
+        c64utils.set_rasterirq_excl(40)     ; register exclusive raster irq handler
 
         while(true) {
+            ; enjoy the moving bars :)
         }
 
     }
@@ -20,22 +21,20 @@
     const ubyte barheight = 4
     ubyte[] colors = [6,2,4,5,15,7,1,13,3,12,8,11,9]
     ubyte color = 0
-    ubyte ypos = 0
+    ubyte yanim = 0
 
     sub irq() {
-        Y++     ; slight timing delay to avoid rasterline transition issues
-        ubyte rasterpos = c64.RASTER
-
         if color!=len(colors) {
             c64.EXTCOL = colors[color]
+            c64.RASTER += barheight         ; next raster Irq for next color
             color++
-            c64.RASTER = rasterpos+barheight
         }
         else {
-            ypos += 2
             c64.EXTCOL = 0
             color = 0
-            c64.RASTER = sin8u(ypos)/2+40
+            yanim += 2
+            c64.RASTER = sin8u(yanim)/2+30  ; new start of raster Irq
         }
+        c64.SCROLY &= $7f    ; set high bit of the raster pos to zero
     }
 }