diff --git a/src/libgetopts/lib.rs b/src/libgetopts/lib.rs
index 79c435f01e4e..38729eece5ab 100644
--- a/src/libgetopts/lib.rs
+++ b/src/libgetopts/lib.rs
@@ -78,7 +78,7 @@
 //! ```
 
 #![crate_name = "getopts"]
-#![experimental]
+#![experimental = "use the crates.io `getopts` library instead"]
 #![crate_type = "rlib"]
 #![crate_type = "dylib"]
 #![doc(html_logo_url = "http://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
diff --git a/src/liblog/lib.rs b/src/liblog/lib.rs
index 0217c5b27138..976b9bcf37eb 100644
--- a/src/liblog/lib.rs
+++ b/src/liblog/lib.rs
@@ -157,7 +157,7 @@
 //! if logging is disabled, none of the components of the log will be executed.
 
 #![crate_name = "log"]
-#![experimental]
+#![experimental = "use the crates.io `log` library instead"]
 #![crate_type = "rlib"]
 #![crate_type = "dylib"]
 #![doc(html_logo_url = "http://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
diff --git a/src/libregex/lib.rs b/src/libregex/lib.rs
index 3fadba9583ec..9ad02afee993 100644
--- a/src/libregex/lib.rs
+++ b/src/libregex/lib.rs
@@ -364,7 +364,7 @@
 #![crate_name = "regex"]
 #![crate_type = "rlib"]
 #![crate_type = "dylib"]
-#![experimental]
+#![experimental = "use the crates.io `regex` library instead"]
 #![doc(html_logo_url = "http://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
        html_favicon_url = "http://www.rust-lang.org/favicon.ico",
        html_root_url = "http://doc.rust-lang.org/nightly/",
diff --git a/src/libregex_macros/lib.rs b/src/libregex_macros/lib.rs
index c1e8677fa8f3..bf1095d21b2f 100644
--- a/src/libregex_macros/lib.rs
+++ b/src/libregex_macros/lib.rs
@@ -13,7 +13,7 @@
 
 #![crate_name = "regex_macros"]
 #![crate_type = "dylib"]
-#![experimental]
+#![experimental = "use the crates.io `regex_macros` library instead"]
 #![doc(html_logo_url = "http://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
        html_favicon_url = "http://www.rust-lang.org/favicon.ico",
        html_root_url = "http://doc.rust-lang.org/nightly/")]