diff --git a/src/main.ts b/src/main.ts
index 0627979ed..7ab33601f 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -1403,7 +1403,7 @@ function generateEncode(ctx: Context, fullName: string, messageDesc: DescriptorP
           writer.ldelim();
         `;
 
-        if (options.forceLong === LongOption.BIGINT) {
+        if (isLong(field) && options.forceLong === LongOption.BIGINT) {
           const fieldType = toReaderCall(field);
           switch (fieldType) {
             case 'int64': case 'sint64': case 'sfixed64':