diff --git a/build.rs b/build.rs
index fc655de..c41a14a 100644
--- a/build.rs
+++ b/build.rs
@@ -10,6 +10,7 @@ fn dlerror_is_mtsafe(target_os: &str) {
         | "macos"
         | "ios"
         | "solaris"
+        | "illumos"
         | "redox"
         | "fuchsia" => {
             println!("cargo:rustc-cfg=mtsafe_dlerror");