diff --git a/rules/aep0131/request_unknown_fields.go b/rules/aep0131/request_unknown_fields.go
index 0e8a8b3..ab30292 100644
--- a/rules/aep0131/request_unknown_fields.go
+++ b/rules/aep0131/request_unknown_fields.go
@@ -25,10 +25,11 @@ import (
 )
 
 var allowedFields = stringset.New(
-	"path",       // AEP-131
-	"request_id", // AEP-155
-	"read_mask",  // AEP-157
-	"view",       // AEP-157
+	"path",         // AEP-131
+	"request_id",   // AEP-155
+	"read_mask",    // AEP-157
+	"view",         // AEP-157
+	"show_deleted", // AEP-164
 )
 
 // Get methods should not have unrecognized fields.
diff --git a/rules/aep0131/request_unknown_fields_test.go b/rules/aep0131/request_unknown_fields_test.go
index 7ba2835..c2c7fa1 100644
--- a/rules/aep0131/request_unknown_fields_test.go
+++ b/rules/aep0131/request_unknown_fields_test.go
@@ -44,6 +44,7 @@ func TestUnknownFields(t *testing.T) {
 		{"Invalid", "GetBookRequest", "application_id", builder.FieldTypeString(), testutils.Problems{{
 			Message: "Unexpected field",
 		}}},
+		{"ShowDeleted", "GetBookRequest", "show_deleted", builder.FieldTypeBool(), testutils.Problems{}},
 		{"Irrelevant", "AcquireBookRequest", "application_id", builder.FieldTypeString(), testutils.Problems{}},
 	}