diff --git a/src/swrenderer/drawers/r_thread.cpp b/src/swrenderer/drawers/r_thread.cpp
index 5aa157f27..5055e259b 100644
--- a/src/swrenderer/drawers/r_thread.cpp
+++ b/src/swrenderer/drawers/r_thread.cpp
@@ -140,8 +140,8 @@ void DrawerThreads::WorkerMain(DrawerThread *thread)
 		// Grab the commands
 		DrawerCommandQueuePtr list = active_commands[thread->current_queue];
 		thread->current_queue++;
-		thread->numa_start_y = thread->numa_node * viewheight / thread->num_numa_nodes;
-		thread->numa_end_y = (thread->numa_node + 1) * viewheight / thread->num_numa_nodes;
+		thread->numa_start_y = thread->numa_node * screen->GetHeight() / thread->num_numa_nodes;
+		thread->numa_end_y = (thread->numa_node + 1) * screen->GetHeight() / thread->num_numa_nodes;
 		start_lock.unlock();
 
 		// Do the work:
diff --git a/src/swrenderer/drawers/r_thread.h b/src/swrenderer/drawers/r_thread.h
index f2d1d4d0e..f12193a49 100644
--- a/src/swrenderer/drawers/r_thread.h
+++ b/src/swrenderer/drawers/r_thread.h
@@ -55,7 +55,7 @@ public:
 
 	// Active range for the numa block the cores are part of
 	int numa_start_y = 0;
-	int numa_end_y = 0;
+	int numa_end_y = MAXHEIGHT;
 
 	// Working buffer used by the tilted (sloped) span drawer
 	const uint8_t *tiltlighting[MAXWIDTH];