diff --git a/Zend/tests/allow_dynamic_properties_on_enum.phpt b/Zend/tests/allow_dynamic_properties_on_enum.phpt
new file mode 100644
index 0000000000000..b9ab745be9ae7
--- /dev/null
+++ b/Zend/tests/allow_dynamic_properties_on_enum.phpt
@@ -0,0 +1,11 @@
+--TEST--
+#[AllowDynamicProperties] cannot be applied to enum (GH-15731)
+--FILE--
+<?php
+
+#[AllowDynamicProperties]
+enum Test {}
+
+?>
+--EXPECTF--
+Fatal error: Cannot apply #[AllowDynamicProperties] to enum Test in %s on line %d
diff --git a/Zend/zend_attributes.c b/Zend/zend_attributes.c
index 2471a6739e3c6..51c3eecd7b3c0 100644
--- a/Zend/zend_attributes.c
+++ b/Zend/zend_attributes.c
@@ -84,6 +84,11 @@ static void validate_allow_dynamic_properties(
 			ZSTR_VAL(scope->name)
 		);
 	}
+	if (scope->ce_flags & ZEND_ACC_ENUM) {
+		zend_error_noreturn(E_ERROR, "Cannot apply #[AllowDynamicProperties] to enum %s",
+			ZSTR_VAL(scope->name)
+		);
+	}
 	scope->ce_flags |= ZEND_ACC_ALLOW_DYNAMIC_PROPERTIES;
 }