diff --git a/libdevcore/CommonData.h b/libdevcore/CommonData.h
index c39920dce..c157583a2 100644
--- a/libdevcore/CommonData.h
+++ b/libdevcore/CommonData.h
@@ -140,6 +140,12 @@ inline bytes toCompactBigEndian(uint8_t _val, unsigned _min = 0)
 	return (_min || _val) ? bytes{ _val } : bytes{};
 }
 
+/// Workarounds shift left bug in boost <1.65.1.
+template <class S> S bigintShiftLeftWorkaround(S const& _a, unsigned _b)
+{
+	return (S)(bigint(_a) << _b);
+}
+
 /// Convenience function for conversion of a u256 to hex
 inline std::string toHex(u256 val, HexPrefix prefix = HexPrefix::DontAdd)
 {
diff --git a/libevmasm/RuleList.h b/libevmasm/RuleList.h
index 7cdf5a96f..0208a379c 100644
--- a/libevmasm/RuleList.h
+++ b/libevmasm/RuleList.h
@@ -87,12 +87,12 @@ std::vector<SimplificationRule<Pattern>> simplificationRuleListPart1(
 				return B.d();
 			unsigned testBit = unsigned(A.d()) * 8 + 7;
 			u256 mask = (u256(1) << testBit) - 1;
-			return u256(boost::multiprecision::bit_test(B.d(), testBit) ? B.d() | ~mask : B.d() & mask);
+			return boost::multiprecision::bit_test(B.d(), testBit) ? B.d() | ~mask : B.d() & mask;
 		}, false},
 		{{Instruction::SHL, {A, B}}, [=]{
 			if (A.d() > 255)
 				return u256(0);
-			return u256(bigint(B.d()) << unsigned(A.d()));
+			return bigintShiftLeftWorkaround(B.d(), unsigned(A.d()));
 		}, false},
 		{{Instruction::SHR, {A, B}}, [=]{
 			if (A.d() > 255)