diff --git a/src/spicelib/parser/inpptree-parser.y b/src/spicelib/parser/inpptree-parser.y
index c12f0963d..53fd3d884 100644
--- a/src/spicelib/parser/inpptree-parser.y
+++ b/src/spicelib/parser/inpptree-parser.y
@@ -96,6 +96,7 @@ exp:
   | '(' exp ')'                       { $$ = $2; }
 
   | '-' exp  %prec NEG                { $$ = PT_mkfnode("-",$2); }
+  | '+' exp  %prec NEG                { $$ = $2; }
 
   | TOK_STR '(' nonempty_arglist ')'  { $$ = PT_mkfnode($1, $3);
                                         if (!$$)