diff --git a/lib/web/JsonpMainTemplatePlugin.js b/lib/web/JsonpMainTemplatePlugin.js
index ad069d5313b..2a842025b2a 100644
--- a/lib/web/JsonpMainTemplatePlugin.js
+++ b/lib/web/JsonpMainTemplatePlugin.js
@@ -154,6 +154,7 @@ class JsonpMainTemplatePlugin {
 
 				return Template.asString([
 					"var script = document.createElement('script');",
+					"var onScriptComplete;",
 					jsonpScriptType
 						? `script.type = ${JSON.stringify(jsonpScriptType)};`
 						: "",
@@ -168,12 +169,7 @@ class JsonpMainTemplatePlugin {
 					),
 					"}",
 					"script.src = jsonpScriptSrc(chunkId);",
-					"var timeout = setTimeout(function(){",
-					Template.indent([
-						"onScriptComplete({ type: 'timeout', target: script });"
-					]),
-					`}, ${chunkLoadTimeout});`,
-					"function onScriptComplete(event) {",
+					"onScriptComplete = function (event) {",
 					Template.indent([
 						"// avoid mem leaks in IE.",
 						"script.onerror = script.onload = null;",
@@ -196,6 +192,11 @@ class JsonpMainTemplatePlugin {
 						"}"
 					]),
 					"};",
+					"var timeout = setTimeout(function(){",
+					Template.indent([
+						"onScriptComplete({ type: 'timeout', target: script });"
+					]),
+					`}, ${chunkLoadTimeout});`,
 					"script.onerror = script.onload = onScriptComplete;"
 				]);
 			}