diff --git a/libsolidity/ast/AST.cpp b/libsolidity/ast/AST.cpp
index 3c9c64196..5ef986bdc 100644
--- a/libsolidity/ast/AST.cpp
+++ b/libsolidity/ast/AST.cpp
@@ -403,12 +403,11 @@ void StructDefinition::insertEip712EncodedSubtypes(std::set<std::string>& subtyp
 				declaration = m_members[i]->type()->typeDefinition();
 				break;
 			case Type::Category::Array:
+				if (auto const* arrayType = dynamic_cast<ArrayType const*>(m_members[i]->type()))
 				{
-					auto const* arrayType = dynamic_cast<ArrayType const*>(m_members[i]->type());
-					solAssert(!!arrayType);
-					if (auto finalyBaseType = dynamic_cast<StructType const*>(arrayType->finalBaseType(false)))
+					if (auto finalBaseType = dynamic_cast<StructType const*>(arrayType->finalBaseType(false)))
 					{
-						declaration = finalyBaseType->typeDefinition();
+						declaration = finalBaseType->typeDefinition();
 					}
 				}
 				break;
diff --git a/libsolidity/ast/Types.h b/libsolidity/ast/Types.h
index 37cb843e8..667ff3be4 100644
--- a/libsolidity/ast/Types.h
+++ b/libsolidity/ast/Types.h
@@ -357,7 +357,11 @@ public:
 	/// @returns the canonical name of this type for use in library function signatures.
 	virtual std::string canonicalName() const { return toString(true); }
 	virtual std::string humanReadableName() const { return toString(); }
-	virtual std::string eip712TypeName() const { return encodingType()->toString(true); }
+	virtual std::string eip712TypeName() const
+	{
+		solAssert(isEIP712AllowedStructMemberType(), "Invalid type ...");
+		return encodingType()->toString(true);
+	}
 	virtual bool isEIP712AllowedStructMemberType() const { return false; }
 	/// @returns the signature of this type in external functions, i.e. `uint256` for integers
 	/// or `(uint256,bytes8)[2]` for an array of structs. If @a _structsByName,