diff --git a/specs/udmf_zdoom.txt b/specs/udmf_zdoom.txt
index 6541e9a02..d501cb884 100644
--- a/specs/udmf_zdoom.txt
+++ b/specs/udmf_zdoom.txt
@@ -237,6 +237,7 @@ Note: All <bool> fields default to false unless mentioned otherwise.
 	  scalex = <float>;         // Vertical scaling on thing. Default = 0 (ignored).
 	  scaley = <float>;         // Horizontal scaling on thing. Default = 0 (ignored).
 	  scale = <float>;        	// Vertical and horizontal scaling on thing. Default = 0 (ignored).
+	  floatbobphase = <int>;	// Sets the thing's floatbobphase. Valid phase values are 0-63. Default = -1 (use actor class default).
 
       * Note about arg0str
 
diff --git a/src/doomdata.h b/src/doomdata.h
index 71e581e26..0877aee90 100644
--- a/src/doomdata.h
+++ b/src/doomdata.h
@@ -365,6 +365,7 @@ struct FMapThing
 	short		pitch;
 	short		roll;
 	DWORD		RenderStyle;
+	int			FloatbobPhase;
 };
 
 
diff --git a/src/namedef.h b/src/namedef.h
index 0d49bba76..22dbe1b51 100644
--- a/src/namedef.h
+++ b/src/namedef.h
@@ -396,6 +396,7 @@ xx(Roll)
 xx(Scale)
 xx(ScaleX)
 xx(ScaleY)
+xx(Floatbobphase)
 
 xx(Blocking)
 xx(Blockmonsters)
diff --git a/src/p_buildmap.cpp b/src/p_buildmap.cpp
index 46c2b9f4c..670f53751 100644
--- a/src/p_buildmap.cpp
+++ b/src/p_buildmap.cpp
@@ -707,6 +707,7 @@ static int LoadSprites (spritetype *sprites, Xsprite *xsprites, int numsprites,
 		mapthings[count].RenderStyle = STYLE_Count;
 		mapthings[count].alpha = -1;
 		mapthings[count].health = -1;
+		mapthings[count].FloatbobPhase = -1;
 
 		if (xsprites != NULL && sprites[i].lotag == 710)
 		{ // Blood ambient sound
diff --git a/src/p_mobj.cpp b/src/p_mobj.cpp
index d5c5eb5d9..ab89ae04c 100644
--- a/src/p_mobj.cpp
+++ b/src/p_mobj.cpp
@@ -4917,6 +4917,7 @@ AActor *P_SpawnMapThing (FMapThing *mthing, int position)
 	mobj->SpawnPoint[2] = mthing->z;
 	mobj->SpawnAngle = mthing->angle;
 	mobj->SpawnFlags = mthing->flags;
+	if (mthing->FloatbobPhase >= 0 && mthing->FloatbobPhase < 64) mobj->FloatBobPhase = mthing->FloatbobPhase;
 	if (mthing->gravity < 0) mobj->gravity = -mthing->gravity;
 	else if (mthing->gravity > 0) mobj->gravity = FixedMul(mobj->gravity, mthing->gravity);
 	else mobj->flags &= ~MF_NOGRAVITY;
diff --git a/src/p_setup.cpp b/src/p_setup.cpp
index 311bf8fc4..50e7f41d6 100644
--- a/src/p_setup.cpp
+++ b/src/p_setup.cpp
@@ -1758,6 +1758,7 @@ void P_LoadThings (MapData * map)
 		mti[i].RenderStyle = STYLE_Count;
 		mti[i].alpha = -1;
 		mti[i].health = 1;
+		mti[i].FloatbobPhase = -1;
 		flags &= ~MTF_SKILLMASK;
 		mti[i].flags = (short)((flags & 0xf) | 0x7e0);
 		if (gameinfo.gametype == GAME_Strife)
@@ -1842,6 +1843,7 @@ void P_LoadThings2 (MapData * map)
 		mti[i].RenderStyle = STYLE_Count;
 		mti[i].alpha = -1;
 		mti[i].health = 1;
+		mti[i].FloatbobPhase = -1;
 	}
 	delete[] mtp;
 }
diff --git a/src/p_udmf.cpp b/src/p_udmf.cpp
index 0434d8bce..269ce7e3d 100644
--- a/src/p_udmf.cpp
+++ b/src/p_udmf.cpp
@@ -474,6 +474,7 @@ public:
 		th->RenderStyle = STYLE_Count;
 		th->alpha = -1;
 		th->health = 1;
+		th->FloatbobPhase = -1;
 		sc.MustGetToken('{');
 		while (!sc.CheckToken('}'))
 		{
@@ -631,6 +632,11 @@ public:
 				Flag(th->flags, MTF_SECRET, key); 
 				break;
 
+			case NAME_Floatbobphase:
+				CHECK_N(Zd | Zdt)
+				th->FloatbobPhase = CheckInt(key);
+				break;
+
 			case NAME_Renderstyle:
 				{
 				FName style = CheckString(key);