diff --git a/example/fs/Samples/SampleRunner.fs b/example/fs/Samples/SampleRunner.fs
index 9a180a6..cdb2428 100644
--- a/example/fs/Samples/SampleRunner.fs
+++ b/example/fs/Samples/SampleRunner.fs
@@ -12,6 +12,7 @@
 namespace Samples
 
 open AUTD3Sharp
+open AUTD3Sharp.Gain
 
 module SampleRunner =
     let Run<'T> (autd : Controller<'T>) =