diff --git a/package/rt-tests/Config.in b/package/rt-tests/Config.in
index 0999ebfbce..a040139579 100644
--- a/package/rt-tests/Config.in
+++ b/package/rt-tests/Config.in
@@ -14,6 +14,12 @@ config BR2_PACKAGE_RT_TESTS
 	  installed if a Python interpreter has been selected in the
 	  Buildroot configuration.
 
+	  Note that this package requires a toolchain built with the
+	  NPTL implementation of the pthread API (this is always the
+	  case with glibc/eglibc toolchains, but may not necessarily
+	  be the case with uClibc toolchains, since the thread
+	  implementation is configurable).
+
 	  http://rt.wiki.kernel.org
 
 comment "rt-tests requires a toolchain with threads support"