\r is not a keychar on Windows

lexer.go

diff --git a/lexer.go b/lexer.go
index 5dfff38..67f9ebc 100644
--- a/lexer.go
+++ b/lexer.go
@@ -70,7 +70,7 @@
 func isKeyChar(r rune) bool {
 	// "Keys start with the first non-whitespace character and end with the last
 	// non-whitespace character before the equals sign."
-	return !(isSpace(r) || r == '\n' || r == eof || r == '=')
+	return !(isSpace(r) || r == '\r' || r == '\n' || r == eof || r == '=')
 }
 
 func isDigit(r rune) bool {