diff --git a/src/hb-ot-layout-common.hh b/src/hb-ot-layout-common.hh
index 593b51b9f..36855365b 100644
--- a/src/hb-ot-layout-common.hh
+++ b/src/hb-ot-layout-common.hh
@@ -3900,8 +3900,8 @@ struct ConditionAxisRange
     {
       // add axisIndex->value into the hashmap so we can check if the record is
       // unique with variations
-      int16_t int_filter_max_val = filterRangeMaxValue.to_int ();
-      int16_t int_filter_min_val = filterRangeMinValue.to_int ();
+      uint16_t int_filter_max_val = (uint16_t) filterRangeMaxValue.to_int ();
+      uint16_t int_filter_min_val = (uint16_t) filterRangeMinValue.to_int ();
       hb_codepoint_t val = (int_filter_max_val << 16) + int_filter_min_val;
 
       condition_map->set (axisIndex, val);