diff --git a/src/modules/child_process.c b/src/modules/child_process.c
index 124b7aa..12e6a6c 100644
--- a/src/modules/child_process.c
+++ b/src/modules/child_process.c
@@ -906,7 +906,8 @@ static ant_value_t create_child_stream_object(ant_t *js, child_process_t *cp, ch
   js_set(js, obj, "destroy", js_mkfun(child_stream_destroy));
   js_set(js, obj, "setEncoding", js_mkfun(child_stream_set_encoding));
   js_set(js, obj, "length", js_mknum(0));
-  js_set(js, obj, "readableEncoding", js_mkundef());
+  js_set(js, obj, "encoding", js_mknull());
+  js_set(js, obj, "readableEncoding", js_mknull());
 
   if (kind == CHILD_STREAM_STDIN) {
     js_set(js, obj, "write", js_mkfun(child_stream_write));
diff --git a/tests/test_child_process_stream_setencoding.cjs b/tests/test_child_process_stream_setencoding.cjs
index 6cd1cb0..0bce539 100644
--- a/tests/test_child_process_stream_setencoding.cjs
+++ b/tests/test_child_process_stream_setencoding.cjs
@@ -11,6 +11,8 @@ const child = spawn(process.execPath, [
 
 assert(child.stdout && typeof child.stdout.setEncoding === 'function', 'child.stdout.setEncoding should exist');
 assert(child.stderr && typeof child.stderr.setEncoding === 'function', 'child.stderr.setEncoding should exist');
+assert(child.stdout.readableEncoding === null, 'stdout readableEncoding should start as null');
+assert(child.stderr.readableEncoding === null, 'stderr readableEncoding should start as null');
 assert(child.stdout.setEncoding('utf8') === child.stdout, 'stdout.setEncoding should return stdout');
 assert(child.stderr.setEncoding('utf8') === child.stderr, 'stderr.setEncoding should return stderr');
 assert(child.stdout.readableEncoding === 'utf8', 'stdout readableEncoding should be utf8');