diff --git a/shell/lexer.l b/shell/lexer.l
index 1def144..971a38b 100644
--- a/shell/lexer.l
+++ b/shell/lexer.l
@@ -144,7 +144,7 @@ num          ({num_hex}|{num_dec}|{num_bin}){num_suffix}?
 
 syscall      [%][a-fA-F0-9]+
 option       [a-zA-Z]+=[^ ]*
-symbol       [a-zA-Z_.][a-zA-Z0-9_.]*
+symbol       \.|\.?[a-zA-Z_][a-zA-Z0-9_.]*
 
 space        [ \t]+