diff --git a/src/json_ui.cc b/src/json_ui.cc
index a0294f3e..f4f39b84 100644
--- a/src/json_ui.cc
+++ b/src/json_ui.cc
@@ -257,7 +257,7 @@ void JsonUI::set_on_key(OnKeyCallback callback)
 using JsonArray = Vector<Value>;
 using JsonObject = HashMap<String, Value>;
 
-static bool is_digit_or_minus(char c) { return (c >= '0' and c <= '9') or c == '-'; }
+static bool is_digit(char c) { return c >= '0' and c <= '9'; }
 
 struct JsonResult { Value value; const char* new_pos; };
 
@@ -266,10 +266,10 @@ JsonResult parse_json(const char* pos, const char* end)
     if (not skip_while(pos, end, is_blank))
         return {};
 
-    if (is_digit_or_minus(*pos))
+    if (is_digit(*pos) or *pos == '-')
     {
-        auto digit_end = pos;
-        skip_while(digit_end, end, is_digit_or_minus);
+        auto digit_end = pos + 1;
+        skip_while(digit_end, end, is_digit);
         return { Value{str_to_int({pos, digit_end})}, digit_end };
     }
     if (end - pos > 4 and StringView{pos, pos+4} == "true")