diff --git a/colour.cpp b/colour.cpp
index 10586b9f..ee35eebe 100644
--- a/colour.cpp
+++ b/colour.cpp
@@ -36,7 +36,7 @@ parse_hex (cruft::view<const char*> &str)
     uint8_t g = cruft::ascii::from_hex (str[3]) << 4u | cruft::ascii::from_hex (str[4]);
     uint8_t b = cruft::ascii::from_hex (str[5]) << 4u | cruft::ascii::from_hex (str[6]);
 
-    str = str.consume (7);
+    str = str.consume (7u);
     return cruft::srgba<4,uint8_t> { r, g, b, 255 }.template cast<float> ();
 }