diff --git a/source/image_loader.d b/source/image_loader.d
index 8881591..de7e446 100644
--- a/source/image_loader.d
+++ b/source/image_loader.d
@@ -139,7 +139,7 @@ FIBITMAP* pixmapToFibitmap(Pixmap pixmap)
   FreeImage_SetTagLength(tag, 1);
   FreeImage_SetTagValue(tag, &dismet);
   FreeImage_SetMetadata(FIMD_ANIMATION, img, "DisposalMethod", tag);
-  uint colors = pixmap.palette.length / 3;
+  uint colors = cast(uint)(pixmap.palette.length / 3);
   RGBQUAD* palette = FreeImage_GetPalette(img);
   for (uint c = 0; c < colors; c++)
   {
diff --git a/source/lua_api/fs.d b/source/lua_api/fs.d
index ed68a75..dedf1c4 100644
--- a/source/lua_api/fs.d
+++ b/source/lua_api/fs.d
@@ -85,7 +85,7 @@ void registerFunctions(Program program)
   extern (C) int fs_write(lua_State* L) @trusted
   {
     auto filename = to!string(lua_tostring(L, 1));
-    uint len;
+    size_t len;
     auto str = lua_tolstring(L, 2, &len);
     lua_getglobal(L, "__program");
     auto prog = cast(Program*) lua_touserdata(L, -1);
diff --git a/source/lua_api/view.d b/source/lua_api/view.d
index 0fad255..61a577e 100644
--- a/source/lua_api/view.d
+++ b/source/lua_api/view.d
@@ -108,7 +108,7 @@ void registerFunctions(Program program)
           throw new Exception("Invalid viewport!");
         prog.activeViewport = prog.viewports[cast(uint) vpID];
       }
-      uint id = countUntil(prog.viewports, prog.activeViewport);
+      uint id = cast(uint) countUntil(prog.viewports, prog.activeViewport);
       if (id < 1)
         lua_pushnil(L);
       else
diff --git a/source/machine.d b/source/machine.d
index 323fd91..0726bd2 100644
--- a/source/machine.d
+++ b/source/machine.d
@@ -253,7 +253,7 @@ class Machine
   */
   int getScreenIndex(Viewport screen)
   {
-    return countUntil(this.screens, screen);
+    return cast(int) countUntil(this.screens, screen);
   }
 
   /**
@@ -267,7 +267,7 @@ class Machine
     while (index < 0)
       index += this.screens.length;
     if (index >= this.screens.length)
-      index = this.screens.length - 1;
+      index = cast(int) this.screens.length - 1;
     this.screens = this.screens.remove(i);
     this.screens = this.screens[0 .. index] ~ [cast(Screen) screen] ~ this.screens[index .. $];
   }
diff --git a/source/sample.d b/source/sample.d
index 26c3aa6..a55bb25 100644
--- a/source/sample.d
+++ b/source/sample.d
@@ -89,7 +89,7 @@ class Sample
     uint[] i;
     auto f = File(filename, "wb");
     f.rawWrite("RIFF");
-    i = [36 + this.data.length];
+    i = [36 + cast(uint) this.data.length];
     f.rawWrite(i);
     f.rawWrite("WAVE");
     f.rawWrite("fmt ");
@@ -102,7 +102,7 @@ class Sample
     s = [1, 8];
     f.rawWrite(s);
     f.rawWrite("data");
-    i = [this.data.length];
+    i = [cast(uint) this.data.length];
     f.rawWrite(i);
     b.length = this.data.length;
     for (uint n = 0; n < b.length; n++)
diff --git a/source/viewport.d b/source/viewport.d
index 0005cd3..e5e4649 100644
--- a/source/viewport.d
+++ b/source/viewport.d
@@ -85,7 +85,7 @@ class Viewport
   */
   int getViewportIndex(Viewport vp)
   {
-    return countUntil(this.children, vp);
+    return cast(int) countUntil(this.children, vp);
   }
 
   /**
@@ -99,7 +99,7 @@ class Viewport
     while (index < 0)
       index += this.children.length;
     if (index >= this.children.length)
-      index = this.children.length - 1;
+      index = cast(int) this.children.length - 1;
     this.children = this.children.remove(i);
     this.children = this.children[0 .. index] ~ vp ~ this.children[index .. $];
   }