diff --git a/geom/geom/inc/TGeoPgon.h b/geom/geom/inc/TGeoPgon.h
index 7c26d63aa9250..853fba11091c0 100644
--- a/geom/geom/inc/TGeoPgon.h
+++ b/geom/geom/inc/TGeoPgon.h
@@ -39,7 +39,7 @@ class TGeoPgon : public TGeoPcon {
    {
       thread_local std::vector<ThreadData_t> tdata;
       if (tdata.size() <= fIndex)
-         tdata.resize(std::max<size_t>(fgInstanceCount.load(std::memory_order_relaxed), fIndex + 1));
+         tdata.resize(fIndex + 1);
       ThreadData_t &td = tdata[fIndex];
       if (td.fInitGen != fGeneration.load(std::memory_order_acquire))
          InitThreadSlot(td);
diff --git a/geom/geom/inc/TGeoXtru.h b/geom/geom/inc/TGeoXtru.h
index eb2e21412d3a3..3e1c59c2b6a7f 100644
--- a/geom/geom/inc/TGeoXtru.h
+++ b/geom/geom/inc/TGeoXtru.h
@@ -45,7 +45,7 @@ class TGeoXtru : public TGeoBBox {
    {
       thread_local std::vector<ThreadData_t> tdata;
       if (tdata.size() <= fIndex)
-         tdata.resize(std::max<size_t>(fgInstanceCount.load(std::memory_order_relaxed), fIndex + 1));
+         tdata.resize(fIndex + 1);
       ThreadData_t &td = tdata[fIndex];
       if (td.fInitGen != fGeneration.load(std::memory_order_acquire))
          InitThreadSlot(td);