diff -r e9c3e64fdc84 src/video/cocoa/SDL_cocoamouse.m
--- a/src/video/cocoa/SDL_cocoamouse.m	Sun Sep 18 19:22:09 2016 -0300
+++ b/src/video/cocoa/SDL_cocoamouse.m	Wed Sep 21 11:41:25 2016 -0600
@@ -432,14 +432,14 @@
     }
 
     if (x > 0) {
-        x += 0.9f;
+        x = SDL_ceil(x);
     } else if (x < 0) {
-        x -= 0.9f;
+        x = SDL_floor(x);
     }
     if (y > 0) {
-        y += 0.9f;
+        y = SDL_ceil(y);
     } else if (y < 0) {
-        y -= 0.9f;
+        y = SDL_floor(y);
     }
     SDL_SendMouseWheel(window, mouse->mouseID, (int)x, (int)y, direction);
 }