diff --git a/samples/tetris/src/main/kotlin/SDL_Visualizer.kt b/samples/tetris/src/main/kotlin/SDL_Visualizer.kt
index 44e311f5e46..cdc3b568afc 100644
--- a/samples/tetris/src/main/kotlin/SDL_Visualizer.kt
+++ b/samples/tetris/src/main/kotlin/SDL_Visualizer.kt
@@ -23,7 +23,7 @@ import sdl.*
 fun get_SDL_Error() = SDL_GetError()!!.toKString()
 
 fun sleep(millis: Int) {
-    SDL_Delay(millis)
+    SDL_Delay(millis.toUInt())
 }
 
 class SDL_Visualizer(val width: Int, val height: Int): GameFieldVisualizer, UserInput {
@@ -396,13 +396,13 @@ class SDL_Visualizer(val width: Int, val height: Int): GameFieldVisualizer, User
 
     private fun drawGamePad() {
         if (gamePadButtons == null) return
-        SDL_SetRenderDrawColor(renderer, 127, 127, 127, SDL_ALPHA_OPAQUE.toByte())
+        SDL_SetRenderDrawColor(renderer, 127, 127, 127, SDL_ALPHA_OPAQUE.toUByte())
         fillRect(gamePadButtons.leftRect)
         fillRect(gamePadButtons.downRect)
         fillRect(gamePadButtons.dropRect)
         fillRect(gamePadButtons.rightRect)
         fillRect(gamePadButtons.rotateRect)
-        SDL_SetRenderDrawColor(renderer, 0, 0, 0, SDL_ALPHA_OPAQUE.toByte())
+        SDL_SetRenderDrawColor(renderer, 0, 0, 0, SDL_ALPHA_OPAQUE.toUByte())
     }
 
     private fun fillRect(rect: SDL_Rect) {
diff --git a/samples/tetris/src/main/kotlin/Tetris.kt b/samples/tetris/src/main/kotlin/Tetris.kt
index 10abbc51adf..2c4c2dcb47a 100644
--- a/samples/tetris/src/main/kotlin/Tetris.kt
+++ b/samples/tetris/src/main/kotlin/Tetris.kt
@@ -272,7 +272,7 @@ class GameField(val width: Int, val height: Int, val visualizer: GameFieldVisual
         for (i in 0..height - 1)
             for (j in 0..width - 1)
                 field[i + MARGIN][j + MARGIN] = 0
-        srand(time(null).toInt())
+        srand(time(null).toUInt())
         nextPiece = getNextPiece(false)
         switchCurrentPiece()
     }