diff --git a/src/Language/Wasm/Lexer.x b/src/Language/Wasm/Lexer.x
index 0abf140..6e2b203 100644
--- a/src/Language/Wasm/Lexer.x
+++ b/src/Language/Wasm/Lexer.x
@@ -124,7 +124,7 @@ parseNanSigned :: AlexAction Lexeme
 parseNanSigned = token $ \(pos, _, s, _) len -> 
     let (sign, slen) = parseSign s in
     let num = readHexFromPrefix (len - 6 - slen) $ LBSUtf8.drop (6 + slen) s in
-    Lexeme pos $ TFloatLit $ sign $ fromIntegral num
+    Lexeme pos $ TFloatLit $ sign $ nanWithPayload $ fromIntegral num
 
 parseDecimalSignedInt :: AlexAction Lexeme
 parseDecimalSignedInt = token $ \(pos, _, s, _) len ->