--- a/toolkit/library/rust/shared/Cargo.toml
+++ b/toolkit/library/rust/shared/Cargo.toml
@@ -20,17 +20,16 @@ cubeb-sys = { version = "0.5.0", optiona
 encoding_c = "0.8.0"
 encoding_glue = { path = "../../../../intl/encoding_glue" }
 audioipc-client = { path = "../../../../media/audioipc/client", optional = true }
 audioipc-server = { path = "../../../../media/audioipc/server", optional = true }
 u2fhid = { path = "../../../../dom/webauthn/u2f-hid-rs" }
 rsdparsa_capi = { path = "../../../../media/webrtc/signaling/src/sdp/rsdparsa_capi" }
 # We have these to enforce common feature sets for said crates.
 log = {version = "0.3", features = ["release_max_level_info"]}
-syn = { version = "0.11", features = ["full", "visit", "parsing"] }
 cose-c = { version = "0.1.5" }
 
 [features]
 default = []
 bindgen = ["geckoservo/bindgen"]
 servo = ["geckoservo"]
 quantum_render = ["webrender_bindings"]
 cubeb-remoting = ["cubeb-sys", "audioipc-client", "audioipc-server"]

--- a/toolkit/library/rust/shared/lib.rs
+++ b/toolkit/library/rust/shared/lib.rs
@@ -19,17 +19,16 @@ extern crate cubeb_pulse;
 extern crate encoding_c;
 extern crate encoding_glue;
 #[cfg(feature = "cubeb-remoting")]
 extern crate audioipc_client;
 #[cfg(feature = "cubeb-remoting")]
 extern crate audioipc_server;
 extern crate u2fhid;
 extern crate log;
-extern crate syn;
 extern crate cosec;
 extern crate rsdparsa_capi;
 
 use std::boxed::Box;
 use std::ffi::CStr;
 use std::os::raw::c_char;
 use std::panic;