diff --git a/libdevcore/UTF8.h b/libdevcore/UTF8.h
index 3e39273cd..9bdc2b4f2 100644
--- a/libdevcore/UTF8.h
+++ b/libdevcore/UTF8.h
@@ -29,7 +29,7 @@ namespace dev
 {
 
 /// Validate an input for UTF8 encoding
-/// @returns true if it is invalid and the first invalid position in invalidPosition
+/// @returns false if it is invalid and the first invalid position in invalidPosition
 bool validate(std::string const& _input, size_t& _invalidPosition);
 
 }
diff --git a/libsolidity/ast/Types.cpp b/libsolidity/ast/Types.cpp
index b7de3646c..002ad657b 100644
--- a/libsolidity/ast/Types.cpp
+++ b/libsolidity/ast/Types.cpp
@@ -879,7 +879,8 @@ bool StringLiteralType::isImplicitlyConvertibleTo(Type const& _convertTo) const
 	else if (auto arrayType = dynamic_cast<ArrayType const*>(&_convertTo))
 		return
 			arrayType->isByteArray() &&
-			!(arrayType->dataStoredIn(DataLocation::Storage) && arrayType->isPointer());
+			!(arrayType->dataStoredIn(DataLocation::Storage) && arrayType->isPointer()) &&
+            !(arrayType->isString() && !isValidUTF8());
 	else
 		return false;
 }
@@ -906,6 +907,12 @@ TypePointer StringLiteralType::mobileType() const
 	return make_shared<ArrayType>(DataLocation::Memory, true);
 }
 
+bool StringLiteralType::isValidUTF8() const
+{
+	size_t dontCare {};
+	return dev::validate(m_value, dontCare);
+}
+
 shared_ptr<FixedBytesType> FixedBytesType::smallestTypeForLiteral(string const& _literal)
 {
 	if (_literal.length() <= 32)
diff --git a/libsolidity/ast/Types.h b/libsolidity/ast/Types.h
index b713a7c01..72640a1c4 100644
--- a/libsolidity/ast/Types.h
+++ b/libsolidity/ast/Types.h
@@ -425,6 +425,8 @@ public:
 	virtual std::string toString(bool) const override;
 	virtual TypePointer mobileType() const override;
 
+	bool isValidUTF8() const;
+
 	std::string const& value() const { return m_value; }
 
 private:
diff --git a/test/libsolidity/SolidityNameAndTypeResolution.cpp b/test/libsolidity/SolidityNameAndTypeResolution.cpp
index 6181a8a95..cc4da61b0 100644
--- a/test/libsolidity/SolidityNameAndTypeResolution.cpp
+++ b/test/libsolidity/SolidityNameAndTypeResolution.cpp
@@ -2045,7 +2045,7 @@ BOOST_AUTO_TEST_CASE(invalid_utf8)
 			string s = "\xa0\x00";
 		}
 	)";
-	CHECK_ERROR(sourceCode, TypeError, "Invalid UTF-8");
+	CHECK_ERROR(sourceCode, TypeError, "invalid UTF-8");
 }
 
 BOOST_AUTO_TEST_CASE(string_index)