diff --git a/src/p_saveg.cpp b/src/p_saveg.cpp
index af59924882..b6e3b28ca0 100644
--- a/src/p_saveg.cpp
+++ b/src/p_saveg.cpp
@@ -565,6 +565,7 @@ void P_SerializePolyobjs (FArchive &arc)
 		for(i = 0, po = polyobjs; i < po_NumPolyobjs; i++, po++)
 		{
 			arc << po->tag << po->Angle << po->StartSpot.pos << po->interpolation << po->bBlocked << po->bHasPortals;
+			arc << po->specialdata;
   		}
 	}
 	else
@@ -592,6 +593,10 @@ void P_SerializePolyobjs (FArchive &arc)
 			arc << angle << delta << po->interpolation;
 			arc << po->bBlocked;
 			arc << po->bHasPortals;
+			if (SaveVersion >= 4548)
+			{
+				arc << po->specialdata;
+			}
 
 			po->RotatePolyobj (angle, true);
 			delta -= po->StartSpot.pos;
diff --git a/src/po_man.cpp b/src/po_man.cpp
index 7b5e187a86..001f308f1a 100644
--- a/src/po_man.cpp
+++ b/src/po_man.cpp
@@ -68,27 +68,6 @@ inline FArchive &operator<< (FArchive &arc, podoortype_t &type)
 	return arc;
 }
 
-class DPolyAction : public DThinker
-{
-	DECLARE_CLASS (DPolyAction, DThinker)
-	HAS_OBJECT_POINTERS
-public:
-	DPolyAction (int polyNum);
-	void Serialize (FArchive &arc);
-	void Destroy();
-	void Stop();
-	double GetSpeed() const { return m_Speed; }
-
-	void StopInterpolation ();
-protected:
-	DPolyAction ();
-	int m_PolyObj;
-	double m_Speed;
-	double m_Dist;
-	TObjPtr<DInterpolation> m_Interpolation;
-
-	void SetInterpolation ();
-};
 
 class DRotatePoly : public DPolyAction
 {
@@ -302,6 +281,10 @@ void DMovePoly::Serialize (FArchive &arc)
 {
 	Super::Serialize (arc);
 	arc << m_Angle << m_Speed;
+	if (SaveVersion >= 4548)
+	{
+		arc << m_Speedv;
+	}
 }
 
 DMovePoly::DMovePoly (int polyNum)
diff --git a/src/po_man.h b/src/po_man.h
index 9bc8532552..18b01d9cca 100644
--- a/src/po_man.h
+++ b/src/po_man.h
@@ -5,7 +5,27 @@
 #include "r_defs.h"
 #include "m_bbox.h"
 
-class DPolyAction;
+class DPolyAction : public DThinker
+{
+	DECLARE_CLASS(DPolyAction, DThinker)
+	HAS_OBJECT_POINTERS
+public:
+	DPolyAction(int polyNum);
+	void Serialize(FArchive &arc);
+	void Destroy();
+	void Stop();
+	double GetSpeed() const { return m_Speed; }
+
+	void StopInterpolation();
+protected:
+	DPolyAction();
+	int m_PolyObj;
+	double m_Speed;
+	double m_Dist;
+	TObjPtr<DInterpolation> m_Interpolation;
+
+	void SetInterpolation();
+};
 
 struct FPolyVertex
 {
@@ -67,7 +87,7 @@ struct FPolyObj
 	int			seqType;
 	double		Size;			// polyobj size (area of POLY_AREAUNIT == size of FRACUNIT)
 	FPolyNode	*subsectorlinks;
-	DPolyAction	*specialdata;	// pointer to a thinker, if the poly is moving
+	TObjPtr<DPolyAction> specialdata;	// pointer to a thinker, if the poly is moving
 	TObjPtr<DInterpolation> interpolation;
 
 	FPolyObj();
diff --git a/src/version.h b/src/version.h
index 52b7ea0ba6..9aa4ad7999 100644
--- a/src/version.h
+++ b/src/version.h
@@ -76,7 +76,7 @@ const char *GetVersionString();
 
 // Use 4500 as the base git save version, since it's higher than the
 // SVN revision ever got.
-#define SAVEVER 4546
+#define SAVEVER 4548
 
 #define SAVEVERSTRINGIFY2(x) #x
 #define SAVEVERSTRINGIFY(x) SAVEVERSTRINGIFY2(x)