diff --git a/src-electron/generator/helper-endpointconfig.js b/src-electron/generator/helper-endpointconfig.js
index 0dfe5bebc1..24a009ce5e 100644
--- a/src-electron/generator/helper-endpointconfig.js
+++ b/src-electron/generator/helper-endpointconfig.js
@@ -828,6 +828,7 @@ async function collectAttributes(db, sessionId, endpointTypes, options) {
           longDefaults.push(a)
 
           let def
+          let defArray = []
           if (
             types.isString(a.type) &&
             attributeDefaultValue === null &&
@@ -836,26 +837,34 @@ async function collectAttributes(db, sessionId, endpointTypes, options) {
             // We don't want to make longTypeDefaultValue know about our null
             // string representation.
             if (types.isOneBytePrefixedString(a.type)) {
-              def = ['0xFF']
+              defArray = ['0xFF']
             } else if (types.isTwoBytePrefixedString(a.type)) {
-              def = ['0xFF', '0xFF']
+              defArray = ['0xFF', '0xFF']
             } else {
               throw new Error(`Unknown string type: ${type}`)
             }
+            longDef = {
+              value: defArray,
+              size: defaultSize,
+              index: longDefaultsIndex,
+              name: a.name,
+              comment: cluster.comment,
+              type: a.type,
+            }
           } else {
             def = types.longTypeDefaultValue(
               defaultSize,
               a.type,
               attributeDefaultValue
             )
-          }
-          let longDef = {
-            value: def,
-            size: defaultSize,
-            index: longDefaultsIndex,
-            name: a.name,
-            comment: cluster.comment,
-            type: a.type,
+            longDef = {
+              value: def,
+              size: defaultSize,
+              index: longDefaultsIndex,
+              name: a.name,
+              comment: cluster.comment,
+              type: a.type,
+            }
           }
           attributeDefaultValue = `ZAP_LONG_DEFAULTS_INDEX(${longDefaultsIndex})`
           defaultValueIsMacro = true