diff --git a/shared/libebm/PartitionOneDimensionalBoosting.cpp b/shared/libebm/PartitionOneDimensionalBoosting.cpp
index bfc0210cd..9817eaeff 100644
--- a/shared/libebm/PartitionOneDimensionalBoosting.cpp
+++ b/shared/libebm/PartitionOneDimensionalBoosting.cpp
@@ -350,6 +350,16 @@ static ErrorEbm Flatten(BoosterShell* const pBoosterShell,
 
                EBM_ASSERT(bNominal || pSplit == cSlices - 1 + pInnerTermUpdate->GetSplitPointer(iDimension));
 
+#ifndef NDEBUG
+               UIntSplit prevDebug = 0;
+               for(size_t iDebug = 0; iDebug < cSlices - 1; ++iDebug) {
+                  UIntSplit curDebug = pInnerTermUpdate->GetSplitPointer(iDimension)[iDebug];
+                  EBM_ASSERT(prevDebug < curDebug);
+                  prevDebug = curDebug;
+               }
+               EBM_ASSERT(prevDebug < cBins);
+#endif
+
                LOG_0(Trace_Verbose, "Exited Flatten");
                return Error_None;
             }