diff --git a/Rich/RichFutureRecPhotonAlgorithms/src/RichSIMDQuarticPhotonReco.cpp b/Rich/RichFutureRecPhotonAlgorithms/src/RichSIMDQuarticPhotonReco.cpp
index 957c0f74cfa0759eb2030d291f9110a551a5bd42..e63d932318fd6d3e377eb2aa62ada3fd79801dd8 100644
--- a/Rich/RichFutureRecPhotonAlgorithms/src/RichSIMDQuarticPhotonReco.cpp
+++ b/Rich/RichFutureRecPhotonAlgorithms/src/RichSIMDQuarticPhotonReco.cpp
@@ -234,7 +234,7 @@ SIMDQuarticPhotonReco::operator()( const LHCb::RichTrackSegment::Vector&     seg
   auto& [photons, relations, mirrorData] = outData;
 
   // guess at reserve size. Better to be a bit to big than too small...
-  const auto resSize = ( segments.size() * pixels.size() ) / 8;
+  const auto resSize = ( segments.size() * pixels.size() ) / 32;
   photons.reserve( resSize );
   relations.reserve( resSize );
   // only need to reserve mirror data vector if it is to be filled.