diff --git a/reactos/dll/win32/gdi32/objects/dc.c b/reactos/dll/win32/gdi32/objects/dc.c
index 38563579b7e..610a31b08e9 100644
--- a/reactos/dll/win32/gdi32/objects/dc.c
+++ b/reactos/dll/win32/gdi32/objects/dc.c
@@ -1275,8 +1275,13 @@ SetMapMode(
       return 0;
     }
 #endif
-  if ((Mode == Dc_Attr->iMapMode) && (Mode != MM_ISOTROPIC)) return Mode;
-  return GetAndSetDCDWord( hdc, GdiGetSetMapMode, Mode, 0, 0, 0 );
+  // Force change if Isotropic is set for recompute.
+  if ((Mode != Dc_Attr->iMapMode) || (Mode == MM_ISOTROPIC))
+  {
+      Dc_Attr->ulDirty_ &= ~SLOW_WIDTHS;
+      return GetAndSetDCDWord( hdc, GdiGetSetMapMode, Mode, 0, 0, 0 );
+  }
+  return Dc_Attr->iMapMode;
 }
 
 /*
diff --git a/reactos/subsystems/win32/win32k/objects/coord.c b/reactos/subsystems/win32/win32k/objects/coord.c
index 305c0737d67..1c0d53f43eb 100644
--- a/reactos/subsystems/win32/win32k/objects/coord.c
+++ b/reactos/subsystems/win32/win32k/objects/coord.c
@@ -657,12 +657,10 @@ IntGdiSetMapMode(PDC  dc,
 
   PrevMapMode = Dc_Attr->iMapMode;
 
-  if (MapMode != Dc_Attr->iMapMode || (MapMode != MM_ISOTROPIC && MapMode != MM_ANISOTROPIC))
-  {
-    Dc_Attr->iMapMode = MapMode;
+  Dc_Attr->iMapMode = MapMode;
 
-    switch (MapMode)
-    {
+  switch (MapMode)
+  {
       case MM_TEXT:
         Dc_Attr->szlWindowExt.cx = 1;
         Dc_Attr->szlWindowExt.cy = 1;
@@ -717,7 +715,6 @@ IntGdiSetMapMode(PDC  dc,
       default:
         Dc_Attr->iMapMode = PrevMapMode;
         PrevMapMode = 0;
-    }
 
     DC_UpdateXforms(dc);
   }