diff --git a/src/rendering/hwrenderer/doom_levelmesh.cpp b/src/rendering/hwrenderer/doom_levelmesh.cpp
index 03e0ab2dc..aee1bfeb6 100644
--- a/src/rendering/hwrenderer/doom_levelmesh.cpp
+++ b/src/rendering/hwrenderer/doom_levelmesh.cpp
@@ -2238,11 +2238,11 @@ DEFINE_ACTION_FUNCTION(_Lightmap, Invalidate)
 DEFINE_ACTION_FUNCTION(_Lightmap, SetSunDirection)
 {
 	PARAM_PROLOGUE;
-	PARAM_FLOAT(x);
-	PARAM_FLOAT(y);
-	PARAM_FLOAT(z);
+	PARAM_FLOAT(ang);
+	PARAM_FLOAT(pch);
 
-	auto vec = FVector3(float(x), float(y), float(z));
+	double cosp = g_cos(pch);
+	auto vec = FVector3(float(g_cos(ang) * cosp), float(g_sin(ang) * cosp), float(-g_sin(pch)));
 
 	if (!vec.isZero() && level.levelMesh)
 	{
diff --git a/wadsrc/static/zscript/doombase.zs b/wadsrc/static/zscript/doombase.zs
index f1fd4f8de..8f055e1ed 100644
--- a/wadsrc/static/zscript/doombase.zs
+++ b/wadsrc/static/zscript/doombase.zs
@@ -817,9 +817,9 @@ struct Lightmap
 	// Mark all lightmap surfaces for recalculation. The internal lightmapper will gradually recalculate every single lightmap surface in the level.
 	native static void Invalidate();
 
-	// Set direction of the light towards the sun.
+	// Set direction of the light towards the sun. Angle and pitch matches ZDRayInfo.
 	// Calling this does NOT recalculate the lightmap.
-	native static void SetSunDirection(Vector3 dir);
+	native static void SetSunDirection(double ang, double pch);
 
 	// Can go above 1.0 (call Invalidate())
 	// Calling this does NOT recalculate the lightmap.