diff --git a/src/libstd/sys/unix/c.rs b/src/libstd/sys/unix/c.rs
index 431312b3d8f..99a6731c57d 100644
--- a/src/libstd/sys/unix/c.rs
+++ b/src/libstd/sys/unix/c.rs
@@ -135,7 +135,9 @@ extern {
     pub fn sigaltstack(ss: *const sigaltstack,
                        oss: *mut sigaltstack) -> libc::c_int;
 
+    #[cfg(not(target_os = "android"))]
     pub fn sigemptyset(set: *mut sigset_t) -> libc::c_int;
+
     pub fn pthread_sigmask(how: libc::c_int, set: *const sigset_t,
                            oldset: *mut sigset_t) -> libc::c_int;
 
@@ -155,6 +157,14 @@ extern {
                     -> *mut libc::c_char;
 }
 
+// Ugh. This is only available as an inline until Android API 21.
+#[cfg(target_os = "android")]
+pub unsafe fn sigemptyset(set: *mut sigset_t) -> libc::c_int {
+    use intrinsics;
+    intrinsics::write_bytes(set, 0, 1);
+    return 0;
+}
+
 #[cfg(any(target_os = "linux",
           target_os = "android"))]
 mod signal_os {
diff --git a/src/libstd/sys/unix/process.rs b/src/libstd/sys/unix/process.rs
index 85ce8d79880..695d0ddfaaf 100644
--- a/src/libstd/sys/unix/process.rs
+++ b/src/libstd/sys/unix/process.rs
@@ -446,12 +446,22 @@ mod tests {
     use mem;
     use ptr;
     use libc;
+    use slice;
     use sys::{self, c, cvt, pipe};
 
+    #[cfg(not(target_os = "android"))]
     extern {
         fn sigaddset(set: *mut c::sigset_t, signum: libc::c_int) -> libc::c_int;
     }
 
+    #[cfg(target_os = "android")]
+    unsafe fn sigaddset(set: *mut c::sigset_t, signum: libc::c_int) -> libc::c_int {
+        let raw = slice::from_raw_parts_mut(set as *mut u8, mem::size_of::<c::sigset_t>());
+        let bit = (signum - 1) as usize;
+        raw[bit / 8] |= 1 << (bit % 8);
+        return 0;
+    }
+
     #[test]
     fn test_process_mask() {
         unsafe {