diff --git a/src/3rdparty/harfbuzz/src/harfbuzz-shaper.cpp b/src/3rdparty/harfbuzz/src/harfbuzz-shaper.cpp
index 6f663d5f9b..1024c8162f 100644
--- a/src/3rdparty/harfbuzz/src/harfbuzz-shaper.cpp
+++ b/src/3rdparty/harfbuzz/src/harfbuzz-shaper.cpp
@@ -884,7 +884,7 @@ HB_Bool HB_SelectScript(HB_ShaperItem *shaper_item, const HB_OpenTypeFeature *fe
 
 static HB_Bool containsSurrogates(HB_ShaperItem *item)
 {
-    for (hb_uint32 i=0; i<item->stringLength; ++i) {
+    for (hb_uint32 i=item->item.pos; i<item->item.pos+item->item.length; ++i) {
         HB_UChar16 ucs = item->string[i];
         if ( HB_IsHighSurrogate(ucs) || HB_IsLowSurrogate(ucs) )
             return true;