diff --git a/nimPNG.nim b/nimPNG.nim
index 3e94bf5..9a6d38b 100644
--- a/nimPNG.nim
+++ b/nimPNG.nim
@@ -254,10 +254,10 @@ proc makeChunkType*(val: string): PNGChunkType =
 proc `$`*(tag: PNGChunkType): string =
   result = newString(4)
   let t = int(tag)
-  result[0] = chr(toU32(t shr 24) and 0xFF)
-  result[1] = chr(toU32(t shr 16) and 0xFF)
-  result[2] = chr(toU32(t shr 8) and 0xFF)
-  result[3] = chr(toU32(t) and 0xFF)
+  result[0] = chr(uint32(t shr 24) and 0xFF)
+  result[1] = chr(uint32(t shr 16) and 0xFF)
+  result[2] = chr(uint32(t shr 8) and 0xFF)
+  result[3] = chr(uint32(t) and 0xFF)
 
 proc `==`(a, b: PNGChunkType): bool = int(a) == int(b)
 #proc isAncillary(a: PNGChunkType): bool = (int(a) and (32 shl 24)) != 0
diff --git a/tester/testCodec.nim b/tester/testCodec.nim
index b08fa45..6f4ac49 100644
--- a/tester/testCodec.nim
+++ b/tester/testCodec.nim
@@ -24,7 +24,6 @@ proc getNumColorChannels(colorType: PNGcolorType): int =
   of LCT_PALETTE: result = 1
   of LCT_GREY_ALPHA: result = 2
   of LCT_RGBA: result = 4
-  else: result = 0
 
 proc generateTestImage(width, height: int, colorType = LCT_RGBA, bitDepth = 8): Image =
   new(result)