diff --git a/ts/builder.ts b/ts/builder.ts
index 6be72fb..137031e 100644
--- a/ts/builder.ts
+++ b/ts/builder.ts
@@ -604,7 +604,7 @@
      * @returns list of offsets of each non null object
      */
     createObjectOffsetList(list: string[]): Offset[] {
-      const ret = [];
+      const ret: number[] = [];
   
       for(let i = 0; i < list.length; ++i) {
         const val = list[i];
@@ -625,4 +625,4 @@
       this.createObjectOffsetList(list);
       return this.endVector();
     }
-  }
\ No newline at end of file
+  }