diff --git a/Zend/tests/bug79779.phpt b/Zend/tests/bug79779.phpt
new file mode 100644
index 00000000000..fe11ed76cc9
--- /dev/null
+++ b/Zend/tests/bug79779.phpt
@@ -0,0 +1,12 @@
+--TEST--
+Bug #79779: Assertion failure when assigning property of string offset by reference
+--FILE--
+<?php
+$str = "";
+$str[1]->a = &$b;
+?>
+--EXPECTF--
+Fatal error: Uncaught Error: Cannot use string offset as an object in %s:%d
+Stack trace:
+#0 {main}
+  thrown in %s on line %d
diff --git a/Zend/zend_execute.c b/Zend/zend_execute.c
index 5df8345c762..4efb80bc728 100644
--- a/Zend/zend_execute.c
+++ b/Zend/zend_execute.c
@@ -1417,9 +1417,21 @@ static zend_never_inline ZEND_COLD void zend_wrong_string_offset(EXECUTE_DATA_D)
 			while (opline < end) {
 				if (opline->op1_type == IS_VAR && opline->op1.var == var) {
 					switch (opline->opcode) {
+						case ZEND_FETCH_OBJ_W:
+						case ZEND_FETCH_OBJ_RW:
+						case ZEND_FETCH_OBJ_FUNC_ARG:
+						case ZEND_FETCH_OBJ_UNSET:
+						case ZEND_ASSIGN_OBJ:
 						case ZEND_ASSIGN_OBJ_OP:
+						case ZEND_ASSIGN_OBJ_REF:
 							msg = "Cannot use string offset as an object";
 							break;
+						case ZEND_FETCH_DIM_W:
+						case ZEND_FETCH_DIM_RW:
+						case ZEND_FETCH_DIM_FUNC_ARG:
+						case ZEND_FETCH_DIM_UNSET:
+						case ZEND_FETCH_LIST_W:
+						case ZEND_ASSIGN_DIM:
 						case ZEND_ASSIGN_DIM_OP:
 							msg = "Cannot use string offset as an array";
 							break;
@@ -1437,21 +1449,6 @@ static zend_never_inline ZEND_COLD void zend_wrong_string_offset(EXECUTE_DATA_D)
 						case ZEND_POST_DEC:
 							msg = "Cannot increment/decrement string offsets";
 							break;
-						case ZEND_FETCH_DIM_W:
-						case ZEND_FETCH_DIM_RW:
-						case ZEND_FETCH_DIM_FUNC_ARG:
-						case ZEND_FETCH_DIM_UNSET:
-						case ZEND_FETCH_LIST_W:
-						case ZEND_ASSIGN_DIM:
-							msg = "Cannot use string offset as an array";
-							break;
-						case ZEND_FETCH_OBJ_W:
-						case ZEND_FETCH_OBJ_RW:
-						case ZEND_FETCH_OBJ_FUNC_ARG:
-						case ZEND_FETCH_OBJ_UNSET:
-						case ZEND_ASSIGN_OBJ:
-							msg = "Cannot use string offset as an object";
-							break;
 						case ZEND_ASSIGN_REF:
 						case ZEND_ADD_ARRAY_ELEMENT:
 						case ZEND_INIT_ARRAY: