diff --git a/games/devtest/mods/testentities/visuals.lua b/games/devtest/mods/testentities/visuals.lua
index 26b538e7f..fe611edd2 100644
--- a/games/devtest/mods/testentities/visuals.lua
+++ b/games/devtest/mods/testentities/visuals.lua
@@ -85,6 +85,28 @@ core.register_entity("testentities:sam", {
 	},
 	on_activate = function(self)
 		self.object:set_animation({x = 0, y = 219}, 30, 0, true)
+		self._timer = 0
+		self._grow_head = true
+		self:_animate_head()
+	end,
+	_head_anim_duration = 2,
+	_animate_head = function(self)
+		local s = self._grow_head and 2 or 1
+		self.object:set_bone_override("Head", {
+			scale = {
+				vec = vector.new(s, s, s),
+				absolute = true,
+				interpolation = self._head_anim_duration,
+			},
+		})
+	end,
+	on_step = function(self, dtime)
+		self._timer = self._timer + dtime
+		if self._timer >= self._head_anim_duration then
+			self._timer = 0
+			self._grow_head = not self._grow_head
+			self:_animate_head()
+		end
 	end,
 })
 
diff --git a/irr/src/CAnimatedMeshSceneNode.cpp b/irr/src/CAnimatedMeshSceneNode.cpp
index 7808f1fee..a32706a44 100644
--- a/irr/src/CAnimatedMeshSceneNode.cpp
+++ b/irr/src/CAnimatedMeshSceneNode.cpp
@@ -171,7 +171,8 @@ void CAnimatedMeshSceneNode::OnAnimate(u32 timeMs)
 	}
 
 	// set CurrentFrameNr
-	buildFrameNr(timeMs - LastTimeMs);
+	const u32 dtimeMs = timeMs - LastTimeMs;
+	buildFrameNr(dtimeMs);
 	LastTimeMs = timeMs;
 
 	// This needs to be done on animate, which is called recursively *before*
@@ -183,7 +184,7 @@ void CAnimatedMeshSceneNode::OnAnimate(u32 timeMs)
 	copyOldTransforms();
 
 	if (OnAnimateCallback)
-		OnAnimateCallback(timeMs / 1000.0f);
+		OnAnimateCallback(dtimeMs / 1000.0f);
 
 	IAnimatedMeshSceneNode::OnAnimate(timeMs);