diff --git a/stackit/internal/services/observability/alertgroup/resource.go b/stackit/internal/services/observability/alertgroup/resource.go
index 31a9c3356..c0b24fb15 100644
--- a/stackit/internal/services/observability/alertgroup/resource.go
+++ b/stackit/internal/services/observability/alertgroup/resource.go
@@ -227,7 +227,7 @@ func (a *alertGroupResource) Schema(_ context.Context, _ resource.SchemaRequest,
 							Description: descriptions["expression"],
 							Required:    true,
 							Validators: []validator.String{
-								stringvalidator.LengthBetween(1, 600),
+								stringvalidator.LengthBetween(1, 2000),
 								// The API currently accepts expressions with trailing newlines but does not return them,
 								// leading to inconsistent Terraform results. This issue has been reported to the Obs team.
 								// Until it is resolved, we proactively notify users if their input contains a trailing newline.