diff --git a/musique/errors.cc b/musique/errors.cc
index 39a7e10..de06e1d 100644
--- a/musique/errors.cc
+++ b/musique/errors.cc
@@ -268,7 +268,7 @@ std::ostream& operator<<(std::ostream& os, Error const& err)
 
 		[&](errors::Unsupported_Types_For const& err) {
 			switch (err.type) {
-			case errors::Unsupported_Types_For::Function:
+			break; case errors::Unsupported_Types_For::Function:
 				{
 					os << "I tried to call function '" << err.name << "' but you gave me wrong types for it!\n";
 
@@ -281,9 +281,26 @@ std::ostream& operator<<(std::ostream& os, Error const& err)
 						os << "  " << possibility << '\n';
 					}
 				}
-				break;
-			case errors::Unsupported_Types_For::Operator:
+			break; case errors::Unsupported_Types_For::Operator:
 				{
+					if (err.name == "=") {
+						os << "Operator '=' expects name on it's left side.\n";
+						os << "\n";
+
+						print_error_line(loc);
+
+						pretty::begin_comment(os);
+						os << "If you want to test if two values are equal use '==' operator:\n";
+					  // TODO Maybe we can use code serialization mechanism to print here actual equation
+					  // but transformed to account for use of == operator. If produced string is too big
+					  // then we can skip and show this silly example
+						os << "  3 == 4\n";
+						os << "If you want to change element of an array use update function:\n";
+						os << "  instead of a[i] = x you may write a = update a i x\n";
+						pretty::end(os);
+						return;
+					}
+
 					os << "I tried and failed to evaluate operator '" << err.name << "' due to values with wrong types provided\n";
 					os << "Make sure that both values matches one of supported signatures listed below!\n";
 					os << '\n';
@@ -297,7 +314,6 @@ std::ostream& operator<<(std::ostream& os, Error const& err)
 						os << "  " << possibility << '\n';
 					}
 				}
-				break;
 			}
 		},
 
diff --git a/musique/interpreter/interpreter.cc b/musique/interpreter/interpreter.cc
index ed4aa73..bfb9246 100644
--- a/musique/interpreter/interpreter.cc
+++ b/musique/interpreter/interpreter.cc
@@ -91,8 +91,16 @@ Result<Value> Interpreter::eval(Ast &&ast)
 			if (ast.token.source == "=") {
 				auto lhs = std::move(ast.arguments.front());
 				auto rhs = std::move(ast.arguments.back());
-				ensure(lhs.type == Ast::Type::Literal && lhs.token.type == Token::Type::Symbol,
-					"Currently LHS of assigment must be an identifier"); // TODO(assert)
+
+				if (lhs.type != Ast::Type::Literal || lhs.token.type != Token::Type::Symbol) {
+					return Error {
+						.details = errors::Unsupported_Types_For {
+							.type = errors::Unsupported_Types_For::Operator,
+							.name = "=",
+						},
+						.location = ast.token.location,
+					};
+				}
 
 				Value *v = env->find(std::string(lhs.token.source));
 				ensure(v, "Cannot resolve variable: "s + std::string(lhs.token.source)); // TODO(assert)