diff --git a/include/opp/boundint.h b/include/opp/boundint.h
index d6076a5..4f9f5bd 100644
--- a/include/opp/boundint.h
+++ b/include/opp/boundint.h
@@ -32,6 +32,13 @@ namespace opp {
 			v = k;
 		}
 
+		void operator+=(int k)
+		{
+			k += v;
+			__assume(k >= tmin && k <= tmax);
+			v = k;
+		}
+
 		operator int() const
 		{
 			int k = v;
diff --git a/oscar64/InterCode.cpp b/oscar64/InterCode.cpp
index f9836b3..d0d3230 100644
--- a/oscar64/InterCode.cpp
+++ b/oscar64/InterCode.cpp
@@ -8775,7 +8775,7 @@ void InterCodeBasicBlock::UpdateLocalIntegerRangeSetsForward(const GrowingVariab
 							{
 								vr.mMinState = IntegerValueRange::S_BOUND;
 								vr.mMinValue = 0;
-								vr.LimitMax(ins->mSrc[0].mIntConst);
+								vr.LimitMax(ins->mSrc[0].mIntConst & BuildLowerBitsMask(ins->mSrc[1].mRange.mMaxValue));
 							}
 							else
 							{
@@ -8794,7 +8794,7 @@ void InterCodeBasicBlock::UpdateLocalIntegerRangeSetsForward(const GrowingVariab
 							{
 								vr.mMinState = IntegerValueRange::S_BOUND;
 								vr.mMinValue = 0;
-								vr.LimitMax(ins->mSrc[1].mIntConst);
+								vr.LimitMax(ins->mSrc[1].mIntConst & BuildLowerBitsMask(ins->mSrc[0].mRange.mMaxValue));
 							}
 							else
 							{