diff --git a/bundle/config/mutator/resourcemutator/configure_cluster_policy_definition.go b/bundle/config/mutator/resourcemutator/configure_cluster_policy_definition.go
index c0b1b4b5be7..1e7a0d6f64b 100644
--- a/bundle/config/mutator/resourcemutator/configure_cluster_policy_definition.go
+++ b/bundle/config/mutator/resourcemutator/configure_cluster_policy_definition.go
@@ -45,7 +45,7 @@ func (c configureClusterPolicyDefinition) Apply(_ context.Context, b *bundle.Bun
 				case dyn.KindInvalid, dyn.KindNil, dyn.KindString:
 					// KindInvalid means the field is absent; leave it for backend validation.
 					continue
-				case dyn.KindMap, dyn.KindSequence:
+				case dyn.KindMap:
 					jsonBytes, err := json.Marshal(def.AsAny())
 					if err != nil {
 						return dyn.InvalidValue, fmt.Errorf("failed to marshal inline %s: %w", field, err)
@@ -57,7 +57,7 @@ func (c configureClusterPolicyDefinition) Apply(_ context.Context, b *bundle.Bun
 				default:
 					diags = diags.Append(diag.Diagnostic{
 						Severity:  diag.Error,
-						Summary:   fmt.Sprintf("%s must be a string, map, or sequence, got %s", field, def.Kind()),
+						Summary:   fmt.Sprintf("%s must be a string or map, got %s", field, def.Kind()),
 						Locations: def.Locations(),
 					})
 				}
diff --git a/bundle/config/mutator/resourcemutator/configure_cluster_policy_definition_test.go b/bundle/config/mutator/resourcemutator/configure_cluster_policy_definition_test.go
index 5e9d53fed4a..0c889b94655 100644
--- a/bundle/config/mutator/resourcemutator/configure_cluster_policy_definition_test.go
+++ b/bundle/config/mutator/resourcemutator/configure_cluster_policy_definition_test.go
@@ -27,10 +27,10 @@ func TestConfigureClusterPolicyDefinition(t *testing.T) {
 			want:  `{"spark_version":{"type":"fixed","value":"13.3.x"}}`,
 		},
 		{
-			name:  "definition: inline sequence is marshaled to a JSON string",
-			field: "definition",
-			value: []any{"a", "b"},
-			want:  `["a","b"]`,
+			name:    "definition: inline sequence is rejected",
+			field:   "definition",
+			value:   []any{"a", "b"},
+			wantErr: "definition must be a string or map, got sequence",
 		},
 		{
 			name:  "definition: inline string is left unchanged",
@@ -47,7 +47,7 @@ func TestConfigureClusterPolicyDefinition(t *testing.T) {
 			name:    "definition: non-structured is rejected",
 			field:   "definition",
 			value:   true,
-			wantErr: "definition must be a string, map, or sequence, got bool",
+			wantErr: "definition must be a string or map, got bool",
 		},
 		{
 			// Number stays a JSON number (30, not "30").
@@ -66,7 +66,7 @@ func TestConfigureClusterPolicyDefinition(t *testing.T) {
 			name:    "overrides: non-structured is rejected",
 			field:   "policy_family_definition_overrides",
 			value:   true,
-			wantErr: "policy_family_definition_overrides must be a string, map, or sequence, got bool",
+			wantErr: "policy_family_definition_overrides must be a string or map, got bool",
 		},
 	}