diff --git a/lib/valueflow.cpp b/lib/valueflow.cpp
index ae1232539b97..e3d7a749a70f 100644
--- a/lib/valueflow.cpp
+++ b/lib/valueflow.cpp
@@ -606,7 +606,9 @@ static ValueFlow::Value truncateImplicitConversion(Token* parent, const ValueFlo
 
 static long long truncateIntValue(long long value, size_t value_size, const ValueType::Sign dst_sign)
 {
-    const MathLib::biguint unsignedMaxValue = (1ULL << (value_size * 8)) - 1ULL;
+    MathLib::biguint unsignedMaxValue = -1;
+    if (value_size < sizeof(MathLib::biguint))
+        unsignedMaxValue ^= ~(unsignedMaxValue << (value_size * 8));
     const MathLib::biguint signBit = 1ULL << (value_size * 8 - 1);
     value &= unsignedMaxValue;
     if (dst_sign == ValueType::Sign::SIGNED && (value & signBit))