diff --git a/crates/ra_prof/Cargo.toml b/crates/ra_prof/Cargo.toml
index c33b5121ae..eabfcebb07 100644
--- a/crates/ra_prof/Cargo.toml
+++ b/crates/ra_prof/Cargo.toml
@@ -20,3 +20,8 @@ jemalloc-ctl = { version = "0.3.3", optional = true }
 [features]
 jemalloc = [ "jemallocator", "jemalloc-ctl" ]
 cpu_profiler = []
+
+# Uncomment to enable for the whole crate graph
+# default = [ "backtrace" ]
+# default = [ "jemalloc" ]
+# default = [ "cpu_profiler" ]
diff --git a/crates/ra_prof/src/lib.rs b/crates/ra_prof/src/lib.rs
index 89df7f04b7..0fb4683755 100644
--- a/crates/ra_prof/src/lib.rs
+++ b/crates/ra_prof/src/lib.rs
@@ -43,6 +43,7 @@ pub struct Scope {
 }
 
 impl Scope {
+    #[must_use]
     pub fn enter() -> Scope {
         let prev = IN_SCOPE.with(|slot| std::mem::replace(&mut *slot.borrow_mut(), true));
         Scope { prev }
@@ -78,6 +79,7 @@ pub struct CpuProfiler {
     _private: (),
 }
 
+#[must_use]
 pub fn cpu_profiler() -> CpuProfiler {
     #[cfg(feature = "cpu_profiler")]
     {
diff --git a/crates/stdx/src/lib.rs b/crates/stdx/src/lib.rs
index 08ac6f70f3..3b605c79dd 100644
--- a/crates/stdx/src/lib.rs
+++ b/crates/stdx/src/lib.rs
@@ -87,6 +87,8 @@ where
         Ok(())
     }
 }
+
+#[must_use]
 pub fn timeit(label: &'static str) -> impl Drop {
     struct Guard {
         label: &'static str,