diff --git a/Zend/tests/weakrefs/gh20073.phpt b/Zend/tests/weakrefs/gh20073.phpt
new file mode 100644
index 00000000000..b64c1a68d3c
--- /dev/null
+++ b/Zend/tests/weakrefs/gh20073.phpt
@@ -0,0 +1,15 @@
+--TEST--
+GH-20073 (Assertion failure in WeakMap offset operations on reference)
+--FILE--
+<?php
+$obj = new stdClass;
+$map = new WeakMap;
+$integer = 1;
+$map[$obj] = 0;
+$map[$obj] =& $integer;
+$integer++;
+var_dump($map[$obj], $map->offsetGet($obj));
+?>
+--EXPECT--
+int(2)
+int(2)
diff --git a/Zend/zend_weakrefs.c b/Zend/zend_weakrefs.c
index 4830089e509..518d2d8eb9e 100644
--- a/Zend/zend_weakrefs.c
+++ b/Zend/zend_weakrefs.c
@@ -731,7 +731,7 @@ ZEND_METHOD(WeakMap, offsetGet)
 		RETURN_THROWS();
 	}
 
-	ZVAL_COPY(return_value, zv);
+	RETURN_COPY_DEREF(zv);
 }
 
 ZEND_METHOD(WeakMap, offsetSet)