diff --git a/rtengine/histmatching.cc b/rtengine/histmatching.cc
index 48969368f..f91086285 100644
--- a/rtengine/histmatching.cc
+++ b/rtengine/histmatching.cc
@@ -289,7 +289,7 @@ void RawImageSource::getAutoMatchedToneCurve(const ColorManagementParams &cp, st
             histMatchingCache = outCurve;
             *histMatchingParams = cp;
             return;
-        } else if (w * 32 < fw || w * h < 19200) {
+        } else if (w * 33 < fw || w * h < 19200) {
              // Some cameras have extremely small thumbs, for example Canon PowerShot A3100 IS has 128x96 thumbs.
              // For them we skip histogram matching.
              // With 160x120 thumbs from RICOH GR DIGITAL 2 it works fine, so we use 19200 as limit.