diff --git a/libwccl/parser/grammar.g b/libwccl/parser/grammar.g
index e354413c8682082a69c0a5a1224258bbc910110e..b6178c68132013d2398dd528d8428931f63bcc36 100644
--- a/libwccl/parser/grammar.g
+++ b/libwccl/parser/grammar.g
@@ -1089,7 +1089,7 @@ SIGNED_INT
 options {
 	paraphrase = "Signed integer";
 }
-	: ('-'|'+') ('0'..'9')+ 
+	: ('-'|'+') (' '!|'\t'!)* ('0'..'9')+ 
 ;	
 
 UNSIGNED_INT