diff --git a/src/librustc_data_structures/sync.rs b/src/librustc_data_structures/sync.rs
index d935eb7bdab7..c18a5328dd54 100644
--- a/src/librustc_data_structures/sync.rs
+++ b/src/librustc_data_structures/sync.rs
@@ -323,6 +323,7 @@ pub fn take(&self) -> Option<T> {
 }
 
 pub fn assert_sync<T: ?Sized + Sync>() {}
+pub fn assert_send<T: ?Sized + Send>() {}
 pub fn assert_send_val<T: ?Sized + Send>(_t: &T) {}
 pub fn assert_send_sync_val<T: ?Sized + Sync + Send>(_t: &T) {}
 
diff --git a/src/librustc_driver/driver.rs b/src/librustc_driver/driver.rs
index 0204d041a242..bfff592a5dd4 100644
--- a/src/librustc_driver/driver.rs
+++ b/src/librustc_driver/driver.rs
@@ -402,14 +402,15 @@ pub struct CompileController<'a> {
 
     /// Allows overriding default rustc query providers,
     /// after `default_provide` has installed them.
-    pub provide: Box<dyn Fn(&mut ty::query::Providers) + 'a>,
+    pub provide: Box<dyn Fn(&mut ty::query::Providers) + 'a + sync::Send>,
     /// Same as `provide`, but only for non-local crates,
     /// applied after `default_provide_extern`.
-    pub provide_extern: Box<dyn Fn(&mut ty::query::Providers) + 'a>,
+    pub provide_extern: Box<dyn Fn(&mut ty::query::Providers) + 'a + sync::Send>,
 }
 
 impl<'a> CompileController<'a> {
     pub fn basic() -> CompileController<'a> {
+        sync::assert_send::<Self>();
         CompileController {
             after_parse: PhaseController::basic(),
             after_expand: PhaseController::basic(),
@@ -499,7 +500,7 @@ pub struct PhaseController<'a> {
     // If true then the compiler will try to run the callback even if the phase
     // ends with an error. Note that this is not always possible.
     pub run_callback_on_error: bool,
-    pub callback: Box<dyn Fn(&mut CompileState) + 'a>,
+    pub callback: Box<dyn Fn(&mut CompileState) + 'a + sync::Send>,
 }
 
 impl<'a> PhaseController<'a> {