diff --git a/source/duke3d/src/actors.cpp b/source/duke3d/src/actors.cpp
index b9c420ead..d5a5ad060 100644
--- a/source/duke3d/src/actors.cpp
+++ b/source/duke3d/src/actors.cpp
@@ -309,12 +309,12 @@ next_sprite:
 // <fromunderp>: below->above change?
 static int32_t Proj_MaybeDoTransport(int32_t spriteNum, const uspritetype * const pSEffector, int32_t fromunderp, int32_t daz)
 {
-    if ((totalclock & (UINT8_MAX-1)) <= actor[spriteNum].lasttransport)
+    if ((totalclock & UINT8_MAX) == actor[spriteNum].lasttransport)
         return 0;
 
     spritetype *const        pSprite = &sprite[spriteNum];
     const uspritetype *const otherse = (uspritetype *)&sprite[pSEffector->owner];
-    actor[spriteNum].lasttransport   = (totalclock + (TICSPERFRAME << 2)) & (UINT8_MAX-1);
+    actor[spriteNum].lasttransport   = (totalclock & UINT8_MAX);
 
     pSprite->x += (otherse->x - pSEffector->x);
     pSprite->y += (otherse->y - pSEffector->y);
@@ -3483,7 +3483,7 @@ ACTOR_STATIC void G_MoveTransports(void)
                 case STAT_FALLER:
                 case STAT_DUMMYPLAYER:
                 {
-                    if ((totalclock & (UINT8_MAX-1)) > actor[sectSprite].lasttransport)
+                    if ((totalclock & UINT8_MAX) != actor[sectSprite].lasttransport)
                     {
                         int const zvel    = sprite[sectSprite].zvel;
                         int const absZvel = klabs(zvel);
@@ -3558,7 +3558,7 @@ ACTOR_STATIC void G_MoveTransports(void)
                                             A_SetSprite(newSprite, CLIPMASK0);
                                         }
 
-                                        actor[sectSprite].lasttransport = (totalclock + (TICSPERFRAME << 2)) & (UINT8_MAX-1);
+                                        actor[sectSprite].lasttransport = (totalclock & UINT8_MAX);
 
                                         sprite[sectSprite].x += sprite[OW(spriteNum)].x - SX(spriteNum);
                                         sprite[sectSprite].y += sprite[OW(spriteNum)].y - SY(spriteNum);
@@ -5664,7 +5664,7 @@ ACTOR_STATIC void G_MoveEffectors(void)   //STATNUM 3
 
             j = pSprite->owner;
 
-            if (sprite[j].lotag == UINT8_MAX)
+            if (sprite[j].lotag == UINT16_MAX)
                 DELETE_SPRITE_AND_CONTINUE(spriteNum);
 
             q = pSector->extra>>3;
diff --git a/source/duke3d/src/sector.cpp b/source/duke3d/src/sector.cpp
index c718a8be3..1e9ff45fe 100644
--- a/source/duke3d/src/sector.cpp
+++ b/source/duke3d/src/sector.cpp
@@ -1191,10 +1191,10 @@ int P_ActivateSwitch(int playerNum, int wallOrSprite, int switchType)
 
     if (switchType == SWITCH_SPRITE) // A wall sprite
     {
-        if (actor[wallOrSprite].lasttransport == (totalclock & (UINT8_MAX-1)))
+        if (actor[wallOrSprite].lasttransport == (totalclock & UINT8_MAX))
             return 0;
 
-        actor[wallOrSprite].lasttransport = (totalclock & (UINT8_MAX-1));
+        actor[wallOrSprite].lasttransport = (totalclock & UINT8_MAX);
 
         if (sprite[wallOrSprite].lotag == 0)
             return 0;