diff --git a/doomsday/plugins/common/include/p_mapspec.h b/doomsday/plugins/common/include/p_mapspec.h
index 21c7542ee6..aa4b35bc65 100644
--- a/doomsday/plugins/common/include/p_mapspec.h
+++ b/doomsday/plugins/common/include/p_mapspec.h
@@ -44,10 +44,10 @@ iterlist_t     *P_GetSectorIterListForTag(int tag, boolean createNewList);
 
 sector_t*       P_GetNextSector(linedef_t *line, sector_t *sec);
 
-sector_t*       P_FindSectorSurroundingLowestFloor(sector_t *sec, float *val);
-sector_t*       P_FindSectorSurroundingHighestFloor(sector_t *sec, float *val);
-sector_t*       P_FindSectorSurroundingLowestCeiling(sector_t *sec, float *val);
-sector_t*       P_FindSectorSurroundingHighestCeiling(sector_t *sec, float *val);
+sector_t*       P_FindSectorSurroundingLowestFloor(sector_t *sec, float max, float *val);
+sector_t*       P_FindSectorSurroundingHighestFloor(sector_t *sec, float min, float *val);
+sector_t*       P_FindSectorSurroundingLowestCeiling(sector_t *sec, float max, float *val);
+sector_t*       P_FindSectorSurroundingHighestCeiling(sector_t *sec, float min, float *val);
 sector_t*       P_FindSectorSurroundingLowestLight(sector_t *sector, float *val);
 sector_t*       P_FindSectorSurroundingHighestLight(sector_t *sector, float *val);
 
diff --git a/doomsday/plugins/common/src/p_ceiling.c b/doomsday/plugins/common/src/p_ceiling.c
index 72d3052109..5d2b08f2a8 100644
--- a/doomsday/plugins/common/src/p_ceiling.c
+++ b/doomsday/plugins/common/src/p_ceiling.c
@@ -347,7 +347,7 @@ static int EV_DoCeiling2(int tag, float basespeed, ceilingtype_e type)
             break;
 
         case CT_RAISETOHIGHEST:
-            P_FindSectorSurroundingHighestCeiling(sec, &ceiling->topHeight);
+            P_FindSectorSurroundingHighestCeiling(sec, 0, &ceiling->topHeight);
 #if __JDOOM64__
             ceiling->topHeight -= 8;   // jd64
 #endif
@@ -367,7 +367,7 @@ static int EV_DoCeiling2(int tag, float basespeed, ceilingtype_e type)
 
             if(bitmipR > 0)
             {
-                P_FindSectorSurroundingHighestCeiling(sec, &ceiling->topHeight);
+                P_FindSectorSurroundingHighestCeiling(sec, 0, &ceiling->topHeight);
                 ceiling->state = CS_UP;
                 ceiling->speed *= bitmipL;
                 ceiling->topHeight -= bitmipR;
diff --git a/doomsday/plugins/common/src/p_door.c b/doomsday/plugins/common/src/p_door.c
index ad661be0c9..95fb700947 100644
--- a/doomsday/plugins/common/src/p_door.c
+++ b/doomsday/plugins/common/src/p_door.c
@@ -356,7 +356,7 @@ static int EV_DoDoor2(int tag, float speed, int topwait, doortype_e type)
         {
 #if __JDOOM__ || __JDOOM64__
         case DT_BLAZECLOSE:
-            P_FindSectorSurroundingLowestCeiling(sec, &door->topHeight);
+            P_FindSectorSurroundingLowestCeiling(sec, (float) MAXINT, &door->topHeight);
             door->topHeight -= 4;
             door->state = DS_DOWN;
             door->speed *= 4;
@@ -364,7 +364,7 @@ static int EV_DoDoor2(int tag, float speed, int topwait, doortype_e type)
             break;
 #endif
         case DT_CLOSE:
-            P_FindSectorSurroundingLowestCeiling(sec, &door->topHeight);
+            P_FindSectorSurroundingLowestCeiling(sec, (float) MAXINT, &door->topHeight);
             door->topHeight -= 4;
             door->state = DS_DOWN;
 #if !__JHEXEN__
@@ -386,7 +386,7 @@ static int EV_DoDoor2(int tag, float speed, int topwait, doortype_e type)
 #if !__JHEXEN__
         case DT_BLAZEOPEN:
             door->state = DS_UP;
-            P_FindSectorSurroundingLowestCeiling(sec, &door->topHeight);
+            P_FindSectorSurroundingLowestCeiling(sec, (float) MAXINT, &door->topHeight);
             door->topHeight -= 4;
 # if __JHERETIC__
             door->speed *= 3;
@@ -401,7 +401,7 @@ static int EV_DoDoor2(int tag, float speed, int topwait, doortype_e type)
         case DT_NORMAL:
         case DT_OPEN:
             door->state = DS_UP;
-            P_FindSectorSurroundingLowestCeiling(sec, &door->topHeight);
+            P_FindSectorSurroundingLowestCeiling(sec, (float) MAXINT, &door->topHeight);
             door->topHeight -= 4;
 
 #if !__JHEXEN__
@@ -856,7 +856,7 @@ boolean EV_VerticalDoor(linedef_t* line, mobj_t* mo)
     }
 
     // find the top and bottom of the movement range
-    P_FindSectorSurroundingLowestCeiling(sec, &door->topHeight);
+    P_FindSectorSurroundingLowestCeiling(sec, (float) MAXINT, &door->topHeight);
     door->topHeight -= 4;
     return true;
 }
@@ -895,7 +895,7 @@ void P_SpawnDoorRaiseIn5Mins(sector_t *sec)
     door->state = DS_INITIALWAIT;
     door->type = DT_RAISEIN5MINS;
     door->speed = DOORSPEED;
-    P_FindSectorSurroundingLowestCeiling(sec, &door->topHeight);
+    P_FindSectorSurroundingLowestCeiling(sec, (float) MAXINT, &door->topHeight);
     door->topHeight -= 4;
     door->topWait = DOORWAIT;
     door->topCountDown = 5 * 60 * TICSPERSEC;
diff --git a/doomsday/plugins/common/src/p_floor.c b/doomsday/plugins/common/src/p_floor.c
index bc29f78662..a5d2d5dbd4 100644
--- a/doomsday/plugins/common/src/p_floor.c
+++ b/doomsday/plugins/common/src/p_floor.c
@@ -636,7 +636,7 @@ int EV_DoFloor(linedef_t *line, floortype_e floortype)
             floor->speed *= 4;
 # endif
 #endif
-            P_FindSectorSurroundingHighestFloor(sec, &floor->floorDestHeight);
+            P_FindSectorSurroundingHighestFloor(sec, -500, &floor->floorDestHeight);
             break;
 
         case FT_LOWERTOLOWEST:
@@ -648,7 +648,8 @@ int EV_DoFloor(linedef_t *line, floortype_e floortype)
             floor->speed *= 4;
 # endif
 #endif
-            P_FindSectorSurroundingLowestFloor(sec, &floor->floorDestHeight);
+            P_FindSectorSurroundingLowestFloor(sec,
+                P_GetFloatp(sec, DMU_FLOOR_HEIGHT), &floor->floorDestHeight);
             break;
 #if __JHEXEN__
         case FT_LOWERBYVALUE:
@@ -671,7 +672,7 @@ int EV_DoFloor(linedef_t *line, floortype_e floortype)
             floor->state = FS_DOWN;
             floor->sector = sec;
             floor->speed = FLOORSPEED * 4;
-            P_FindSectorSurroundingHighestFloor(sec, &floor->floorDestHeight);
+            P_FindSectorSurroundingHighestFloor(sec, -500, &floor->floorDestHeight);
 # if __JHERETIC__
             floor->floorDestHeight += 8;
 # else
@@ -686,7 +687,7 @@ int EV_DoFloor(linedef_t *line, floortype_e floortype)
             floor->state = FS_DOWN;
             floor->sector = sec;
             floor->speed = FLOORSPEED;
-            P_FindSectorSurroundingHighestFloor(sec, &floor->floorDestHeight);
+            P_FindSectorSurroundingHighestFloor(sec, -500, &floor->floorDestHeight);
             if(floor->floorDestHeight != P_GetFloatp(sec,
                                                      DMU_FLOOR_HEIGHT))
                 floor->floorDestHeight += 8;
@@ -698,7 +699,7 @@ int EV_DoFloor(linedef_t *line, floortype_e floortype)
                 floor->state = FS_DOWN;
                 floor->sector = sec;
                 floor->speed = FLOORSPEED * bitmipL;
-                P_FindSectorSurroundingHighestFloor(sec, &floor->floorDestHeight);
+                P_FindSectorSurroundingHighestFloor(sec, -500, &floor->floorDestHeight);
 
                 if(floor->floorDestHeight != P_GetFloatp(sec,
                                                          DMU_FLOOR_HEIGHT))
@@ -742,7 +743,7 @@ int EV_DoFloor(linedef_t *line, floortype_e floortype)
 #if __JHEXEN__
             floor->floorDestHeight = P_GetFloatp(sec, DMU_CEILING_HEIGHT)-8;
 #else
-            P_FindSectorSurroundingLowestCeiling(sec, &floor->floorDestHeight);
+            P_FindSectorSurroundingLowestCeiling(sec, (float) MAXINT, &floor->floorDestHeight);
 
             if(floor->floorDestHeight > P_GetFloatp(sec, DMU_CEILING_HEIGHT))
                 floor->floorDestHeight = P_GetFloatp(sec, DMU_CEILING_HEIGHT);
@@ -760,7 +761,7 @@ int EV_DoFloor(linedef_t *line, floortype_e floortype)
             floor->speed *= 4;
 # endif
 #endif
-            P_FindSectorSurroundingLowestCeiling(sec, &floor->floorDestHeight);
+            P_FindSectorSurroundingLowestCeiling(sec, (float) MAXINT, &floor->floorDestHeight);
 
             if(floor->floorDestHeight > P_GetFloatp(sec, DMU_CEILING_HEIGHT))
                 floor->floorDestHeight = P_GetFloatp(sec, DMU_CEILING_HEIGHT);
@@ -909,7 +910,8 @@ int EV_DoFloor(linedef_t *line, floortype_e floortype)
             floor->state = FS_DOWN;
             floor->sector = sec;
             floor->speed = FLOORSPEED;
-            P_FindSectorSurroundingLowestFloor(sec, &floor->floorDestHeight);
+            P_FindSectorSurroundingLowestFloor(sec,
+                P_GetFloatp(sec, DMU_FLOOR_HEIGHT), &floor->floorDestHeight);
             floor->material = P_GetPtrp(sec, DMU_FLOOR_MATERIAL);
 
             {
diff --git a/doomsday/plugins/common/src/p_mapspec.c b/doomsday/plugins/common/src/p_mapspec.c
index ce7fa7ad97..c7c20319ed 100644
--- a/doomsday/plugins/common/src/p_mapspec.c
+++ b/doomsday/plugins/common/src/p_mapspec.c
@@ -423,13 +423,13 @@ int findExtremalPlaneHeight(void *ptr, void *context)
 /**
  * Find the sector with the lowest floor height in surrounding sectors.
  */
-sector_t* P_FindSectorSurroundingLowestFloor(sector_t* sec, float* val)
+sector_t* P_FindSectorSurroundingLowestFloor(sector_t* sec, float max, float* val)
 {
     findextremalplaneheightparams_t params;
 
     params.baseSec = sec;
     params.flags = FEPHF_MIN | FEPHF_FLOOR;
-    params.val = DDMAXFLOAT;
+    params.val = max;
     params.foundSec = NULL;
     P_Iteratep(sec, DMU_LINEDEF, &params, findExtremalPlaneHeight);
 
@@ -441,13 +441,13 @@ sector_t* P_FindSectorSurroundingLowestFloor(sector_t* sec, float* val)
 /**
  * Find the sector with the highest floor height in surrounding sectors.
  */
-sector_t* P_FindSectorSurroundingHighestFloor(sector_t* sec, float* val)
+sector_t* P_FindSectorSurroundingHighestFloor(sector_t* sec, float min, float* val)
 {
     findextremalplaneheightparams_t params;
 
     params.baseSec = sec;
     params.flags = FEPHF_FLOOR;
-    params.val = DDMINFLOAT;
+    params.val = min;
     params.foundSec = NULL;
     P_Iteratep(sec, DMU_LINEDEF, &params, findExtremalPlaneHeight);
 
@@ -459,13 +459,13 @@ sector_t* P_FindSectorSurroundingHighestFloor(sector_t* sec, float* val)
 /**
  * Find lowest ceiling in the surrounding sector.
  */
-sector_t* P_FindSectorSurroundingLowestCeiling(sector_t *sec, float *val)
+sector_t* P_FindSectorSurroundingLowestCeiling(sector_t *sec, float max, float *val)
 {
     findextremalplaneheightparams_t params;
 
     params.baseSec = sec;
     params.flags = FEPHF_MIN;
-    params.val = DDMAXFLOAT;
+    params.val = max;
     params.foundSec = NULL;
     P_Iteratep(sec, DMU_LINEDEF, &params, findExtremalPlaneHeight);
 
@@ -477,13 +477,13 @@ sector_t* P_FindSectorSurroundingLowestCeiling(sector_t *sec, float *val)
 /**
  * Find highest ceiling in the surrounding sectors.
  */
-sector_t* P_FindSectorSurroundingHighestCeiling(sector_t *sec, float *val)
+sector_t* P_FindSectorSurroundingHighestCeiling(sector_t *sec, float min, float *val)
 {
     findextremalplaneheightparams_t params;
 
     params.baseSec = sec;
     params.flags = 0;
-    params.val = DDMINFLOAT;
+    params.val = min;
     params.foundSec = NULL;
     P_Iteratep(sec, DMU_LINEDEF, &params, findExtremalPlaneHeight);
 
diff --git a/doomsday/plugins/common/src/p_plat.c b/doomsday/plugins/common/src/p_plat.c
index 69a0024316..4785ebd849 100644
--- a/doomsday/plugins/common/src/p_plat.c
+++ b/doomsday/plugins/common/src/p_plat.c
@@ -322,7 +322,8 @@ static int doPlat(linedef_t *line, int tag, plattype_e type, int amount)
             break;
 #endif
         case PT_DOWNWAITUPSTAY:
-            P_FindSectorSurroundingLowestFloor(sec, &plat->low);
+            P_FindSectorSurroundingLowestFloor(sec,
+                P_GetFloatp(sec, DMU_FLOOR_HEIGHT), &plat->low);
 #if __JHEXEN__
             plat->low += 8;
 #else
@@ -345,7 +346,7 @@ static int doPlat(linedef_t *line, int tag, plattype_e type, int amount)
 
 #if __JDOOM64__ || __JHEXEN__
         case PT_UPWAITDOWNSTAY:
-            P_FindSectorSurroundingHighestFloor(sec, &plat->high);
+            P_FindSectorSurroundingHighestFloor(sec, -500, &plat->high);
 
             if(plat->high < floorHeight)
                 plat->high = floorHeight;
@@ -366,7 +367,8 @@ static int doPlat(linedef_t *line, int tag, plattype_e type, int amount)
 #if __JDOOM64__
         case PT_DOWNWAITUPDOOR: // jd64
             plat->speed = PLATSPEED * 8;
-            P_FindSectorSurroundingLowestFloor(sec, &plat->low);
+            P_FindSectorSurroundingLowestFloor(sec,
+                P_GetFloatp(sec, DMU_FLOOR_HEIGHT), &plat->low);
 
             if(plat->low > floorHeight)
                 plat->low = floorHeight;
@@ -400,7 +402,8 @@ static int doPlat(linedef_t *line, int tag, plattype_e type, int amount)
 #if __JDOOM__ || __JDOOM64__
         case PT_DOWNWAITUPSTAYBLAZE:
             plat->speed = PLATSPEED * 8;
-            P_FindSectorSurroundingLowestFloor(sec, &plat->low);
+            P_FindSectorSurroundingLowestFloor(sec,
+                P_GetFloatp(sec, DMU_FLOOR_HEIGHT), &plat->low);
 
             if(plat->low > floorHeight)
                 plat->low = floorHeight;
@@ -412,7 +415,8 @@ static int doPlat(linedef_t *line, int tag, plattype_e type, int amount)
             break;
 #endif
         case PT_PERPETUALRAISE:
-            P_FindSectorSurroundingLowestFloor(sec, &plat->low);
+            P_FindSectorSurroundingLowestFloor(sec,
+                P_GetFloatp(sec, DMU_FLOOR_HEIGHT), &plat->low);
 #if __JHEXEN__
             plat->low += 8;
 #else
@@ -421,7 +425,7 @@ static int doPlat(linedef_t *line, int tag, plattype_e type, int amount)
             if(plat->low > floorHeight)
                 plat->low = floorHeight;
 
-            P_FindSectorSurroundingHighestFloor(sec, &plat->high);
+            P_FindSectorSurroundingHighestFloor(sec, -500, &plat->high);
 
             if(plat->high < floorHeight)
                 plat->high = floorHeight;
diff --git a/doomsday/plugins/common/src/p_xgsec.c b/doomsday/plugins/common/src/p_xgsec.c
index d6512a2d00..26c404c6b8 100644
--- a/doomsday/plugins/common/src/p_xgsec.c
+++ b/doomsday/plugins/common/src/p_xgsec.c
@@ -1279,28 +1279,28 @@ boolean XS_GetPlane(linedef_t* actline, sector_t* sector, int ref,
     if(ref == SPREF_HIGHEST_CEILING)
     {
         otherSec =
-            P_FindSectorSurroundingHighestCeiling(sector, &otherHeight);
+            P_FindSectorSurroundingHighestCeiling(sector, DDMINFLOAT, &otherHeight);
         if(otherSec)
             otherMat = P_GetPtrp(otherSec, DMU_CEILING_MATERIAL);
     }
     else if(ref == SPREF_HIGHEST_FLOOR)
     {
         otherSec =
-            P_FindSectorSurroundingHighestFloor(sector, &otherHeight);
+            P_FindSectorSurroundingHighestFloor(sector, DDMINFLOAT, &otherHeight);
         if(otherSec)
             otherMat = P_GetPtrp(otherSec, DMU_CEILING_MATERIAL);
     }
     else if(ref == SPREF_LOWEST_CEILING)
     {
         otherSec =
-            P_FindSectorSurroundingLowestCeiling(sector, &otherHeight);
+            P_FindSectorSurroundingLowestCeiling(sector, DDMAXFLOAT, &otherHeight);
         if(otherSec)
             otherMat = P_GetPtrp(otherSec, DMU_CEILING_MATERIAL);
     }
     else if(ref == SPREF_LOWEST_FLOOR)
     {
         otherSec =
-            P_FindSectorSurroundingLowestFloor(sector, &otherHeight);
+            P_FindSectorSurroundingLowestFloor(sector, DDMAXFLOAT, &otherHeight);
         if(otherSec)
             otherMat = P_GetPtrp(otherSec, DMU_FLOOR_MATERIAL);
     }
diff --git a/doomsday/plugins/jhexen/include/h2def.h b/doomsday/plugins/jhexen/include/h2def.h
index f016b27f3a..64b32d349d 100644
--- a/doomsday/plugins/jhexen/include/h2def.h
+++ b/doomsday/plugins/jhexen/include/h2def.h
@@ -46,6 +46,37 @@
 #include "version.h"
 #include "info.h"
 
+// Predefined with some OS.
+#ifdef UNIX
+
+#include <limits.h>
+
+#define MAXCHAR     SCHAR_MAX
+#define MAXSHORT    SHRT_MAX
+#define MAXINT      INT_MAX
+#define MAXLONG     LONG_MAX
+
+#define MINCHAR     SCHAR_MIN
+#define MINSHORT    SHRT_MIN
+#define MININT      INT_MIN
+#define MINLONG     LONG_MIN
+
+#else /* not UNIX */
+
+#define MAXCHAR     ((char)0x7f)
+#define MAXSHORT    ((short)0x7fff)
+
+// Max pos 32-bit int.
+#define MAXINT      ((int)0x7fffffff)
+#define MAXLONG     ((long)0x7fffffff)
+#define MINCHAR     ((char)0x80)
+#define MINSHORT    ((short)0x8000)
+
+// Max negative 32-bit integer.
+#define MININT      ((int)0x80000000)
+#define MINLONG     ((long)0x80000000)
+#endif
+
 #define Set                 DD_SetInteger
 #define Get                 DD_GetInteger
 
diff --git a/doomsday/plugins/jhexen/src/p_pillar.c b/doomsday/plugins/jhexen/src/p_pillar.c
index eb2b0e71f4..13cd9e47ea 100644
--- a/doomsday/plugins/jhexen/src/p_pillar.c
+++ b/doomsday/plugins/jhexen/src/p_pillar.c
@@ -179,7 +179,8 @@ int EV_OpenPillar(linedef_t *line, byte *args)
         pillar->sector = sec;
         if(!args[2])
         {
-            P_FindSectorSurroundingLowestFloor(sec, &pillar->floorDest);
+            P_FindSectorSurroundingLowestFloor(sec,
+                P_GetFloatp(sec, DMU_FLOOR_HEIGHT), &pillar->floorDest);
         }
         else
         {
@@ -189,7 +190,7 @@ int EV_OpenPillar(linedef_t *line, byte *args)
 
         if(!args[3])
         {
-            P_FindSectorSurroundingHighestCeiling(sec, &pillar->ceilingDest);
+            P_FindSectorSurroundingHighestCeiling(sec, 0, &pillar->ceilingDest);
         }
         else
         {