diff --git a/src/worldmap.cc b/src/worldmap.cc
index 34148c9..a02914f 100644
--- a/src/worldmap.cc
+++ b/src/worldmap.cc
@@ -745,12 +745,6 @@ static int wmRndCallCount = 0;
 // 0x51DEAC
 static int _terrainCounter = 1;
 
-// 0x51DEB0
-static unsigned int _lastTime_2 = 0;
-
-// 0x51DEB4
-static bool _couldScroll = true;
-
 // 0x51DEC8
 static char* wmRemapSfxList[2] = {
     _aCricket,
@@ -4871,19 +4865,25 @@ static int wmInterfaceScrollPixel(int stepX, int stepY, int dx, int dy, bool* su
 // 0x4C32EC
 static void wmMouseBkProc()
 {
+    // 0x51DEB0
+    static unsigned int lastTime = 0;
+
+    // 0x51DEB4
+    static bool couldScroll = true;
+
     int x;
     int y;
-    mouseGetPositionInWindow(wmBkWin, &x, &y);
+    mouseGetPosition(&x, &y);
 
     int dx = 0;
-    if (x == 639) {
+    if (x == screenGetWidth() - 1) {
         dx = 1;
     } else if (x == 0) {
         dx = -1;
     }
 
     int dy = 0;
-    if (y == 479) {
+    if (y == screenGetHeight() - 1) {
         dy = 1;
     } else if (y == 0) {
         dy = -1;
@@ -4918,13 +4918,13 @@ static void wmMouseBkProc()
         }
 
         unsigned int tick = _get_bk_time();
-        if (getTicksBetween(tick, _lastTime_2) > 50) {
-            _lastTime_2 = _get_bk_time();
+        if (getTicksBetween(tick, lastTime) > 50) {
+            lastTime = _get_bk_time();
             // NOTE: Uninline.
-            wmInterfaceScroll(dx, dy, &_couldScroll);
+            wmInterfaceScroll(dx, dy, &couldScroll);
         }
 
-        if (!_couldScroll) {
+        if (!couldScroll) {
             newMouseCursor += 8;
         }
     } else {