diff --git a/src/unix/mod.rs b/src/unix/mod.rs
index 57de24805a420..a711216eb9780 100644
--- a/src/unix/mod.rs
+++ b/src/unix/mod.rs
@@ -1390,6 +1390,7 @@ extern "C" {
 
     pub fn lockf(fd: ::c_int, cmd: ::c_int, len: ::off_t) -> ::c_int;
 
+    #[cfg(not(target_os = "emscripten"))]
     pub fn adjtime(delta: *const timeval, olddelta: *mut timeval) -> ::c_int;
 }