diff --git a/processor/head.m4 b/processor/head.m4
index 9589b75..27012ef 100644
--- a/processor/head.m4
+++ b/processor/head.m4
@@ -200,7 +200,7 @@ static void xc_fix_method(processor_t *processor, zend_op_array *dst) /* {{{ */
 		SET_IF_SAME_NAME(__isset);
 #endif
 		SET_IF_SAME_NAME(__call);
-#if PHP_MAJOR_VERSION >= 6
+#if defined(ZEND_ENGINE_2_2) || PHP_MAJOR_VERSION >= 6
 		SET_IF_SAME_NAME(__tostring);
 #endif
 
diff --git a/processor/processor.m4 b/processor/processor.m4
index e49c035..fc18451 100644
--- a/processor/processor.m4
+++ b/processor/processor.m4
@@ -347,7 +347,7 @@ DEF_STRUCT_P_FUNC(`zend_class_entry', , `dnl {{{
 #ifdef ZEND_ENGINE_2_1
 	COPY(__unset)
 	COPY(__isset)
-# if PHP_MAJOR_VERSION >= 6
+# if defined(ZEND_ENGINE_2_2) || PHP_MAJOR_VERSION >= 6
 	COPY(__tostring)
 # endif
 #endif