diff --git a/less/variables.less b/less/variables.less
index 59747d5364..4c51ce96f6 100644
--- a/less/variables.less
+++ b/less/variables.less
@@ -187,6 +187,7 @@
 
 // TODO: Rename `@input-border-radius` to `@input-border-radius-base` in v4
 //** Default `.form-control` border radius
+// This has no effect on `<select>`s in some browsers, due to the limited stylability of `<select>`s in CSS.
 @input-border-radius:            @border-radius-base;
 //** Large `.form-control` border radius
 @input-border-radius-large:      @border-radius-large;