diff --git a/grammars/json.gbnf b/grammars/json.gbnf
index 2b370ef64..064a53f8a 100644
--- a/grammars/json.gbnf
+++ b/grammars/json.gbnf
@@ -22,4 +22,4 @@ string ::=
 number ::= ("-"? ([0-9] | [1-9] [0-9]{0,15})) ("." [0-9]+)? ([eE] [-+]? [0-9] [1-9]{0,15})? ws
 
 # Optional space: by convention, applied in this grammar after literal chars when allowed
-ws ::= [ \t\n]{,20}
+ws ::= [ \t\n]{0,20}
diff --git a/grammars/json_arr.gbnf b/grammars/json_arr.gbnf
index d85fc23db..bd1312d96 100644
--- a/grammars/json_arr.gbnf
+++ b/grammars/json_arr.gbnf
@@ -31,4 +31,4 @@ string ::=
 number ::= ("-"? ([0-9] | [1-9] [0-9]{0,15})) ("." [0-9]+)? ([eE] [-+]? [1-9] [0-9]{0,15})? ws
 
 # Optional space: by convention, applied in this grammar after literal chars when allowed
-ws ::= [ \t\n]{,20}
+ws ::= [ \t\n]{0,20}