diff --git a/src/compiler/sema_expr.c b/src/compiler/sema_expr.c
index f2b154b83..bdf665e79 100644
--- a/src/compiler/sema_expr.c
+++ b/src/compiler/sema_expr.c
@@ -5343,6 +5343,7 @@ static bool sema_expr_analyse_and_or(SemaContext *context, Expr *expr, Expr *lef
 	if (!sema_binary_analyse_subexpr(context, expr, left, right)) return false;
 	if (!cast_explicit(context, left, type_bool) || !cast_explicit(context, right, type_bool)) return false;
 
+
 	if (expr_both_const(left, right) && sema_constant_fold_ops(left))
 	{
 		if (expr->binary_expr.operator == BINARYOP_AND)
@@ -5356,7 +5357,7 @@ static bool sema_expr_analyse_and_or(SemaContext *context, Expr *expr, Expr *lef
 			expr->const_expr.b |= right->const_expr.b;
 		}
 	}
-	expr->type = type_bool;
+	expr->type = type_add_optional(type_bool, IS_OPTIONAL(left) || IS_OPTIONAL(right));
 	return true;
 }
 
diff --git a/src/version.h b/src/version.h
index e9366a010..83a7c08a7 100644
--- a/src/version.h
+++ b/src/version.h
@@ -1 +1 @@
-#define COMPILER_VERSION "0.4.579"
\ No newline at end of file
+#define COMPILER_VERSION "0.4.580"
\ No newline at end of file
diff --git a/test/test_suite/expressions/optional_and_error.c3 b/test/test_suite/expressions/optional_and_error.c3
new file mode 100644
index 000000000..e9861d494
--- /dev/null
+++ b/test/test_suite/expressions/optional_and_error.c3
@@ -0,0 +1,13 @@
+module testing;
+import std::io;
+
+fn void! main()
+{
+    bool ok;
+    if (ok && !foo()) io::printfn("nok"); // #error: The expression may not be an optional
+}
+
+fn bool! foo()
+{
+    return false;
+}
\ No newline at end of file