diff --git a/sgx_urts/Cargo.toml b/sgx_urts/Cargo.toml
index 36fa7831b..64e634d34 100644
--- a/sgx_urts/Cargo.toml
+++ b/sgx_urts/Cargo.toml
@@ -16,6 +16,7 @@ crate-type = ["rlib"]
 default = []
 global_init = []
 global_exit = []
+signal = []
 
 
 [dependencies]
diff --git a/sgx_urts/src/lib.rs b/sgx_urts/src/lib.rs
index 6fe7b3bfc..6c86dbd04 100644
--- a/sgx_urts/src/lib.rs
+++ b/sgx_urts/src/lib.rs
@@ -32,6 +32,7 @@ pub mod pipe;
 pub mod event;
 pub mod thread;
 pub mod net;
+#[cfg(feature = "signal")]
 pub mod signal;
 pub mod process;
 pub use enclave::*;
diff --git a/sgx_urts/src/signal.rs b/sgx_urts/src/signal.rs
index 0672d9835..d1b356f99 100644
--- a/sgx_urts/src/signal.rs
+++ b/sgx_urts/src/signal.rs
@@ -41,7 +41,7 @@ extern "C" {
 pub struct SigNum(i32);
 
 impl SigNum {
-    // add code here
+
     pub fn from_raw(signo: i32) -> Option<SigNum> {
         if signo <= 0 || signo >= NSIG {
             None
@@ -59,7 +59,7 @@ impl SigNum {
 pub struct SigSet(sigset_t);
 
 impl SigSet {
-    // add code here
+
     pub fn new() -> SigSet {
         let set = unsafe {
             let mut set: sigset_t = mem::zeroed();
@@ -82,7 +82,7 @@ struct GlobalData {
 }
 
 impl GlobalData {
-     // add code here
+
     fn get() -> &'static GlobalData {
         unsafe { GLOBAL_DATA.as_ref().unwrap() }
     }
@@ -101,7 +101,7 @@ struct SignalDispatcher {
 }
 
 impl SignalDispatcher {
-    // add code here
+
     pub fn new () -> SignalDispatcher {
         SignalDispatcher {
             signal_set: Mutex::new(HashMap::new()),