diff --git a/.cargo/config.toml b/.cargo/config.toml
index 34c30d13f..e2e5fa90e 100644
--- a/.cargo/config.toml
+++ b/.cargo/config.toml
@@ -1,9 +1,11 @@
 [env]
 # In unoptimised builds tokio tends to use a lot of stack space when
-# creating some complicated futures.  Some of our tests manage to not
-# fit in the default 2MiB stack anymore due to this.  Because
-# compiling optimised builds takes a very long time we prefer to avoid
-# that.  Setting this environment variable ensures that when invoking
-# `cargo test` threads are allowed to have a large enough stack size
-# without needing to use an optimised build.
+# creating some complicated futures, tokio has an open issue for this:
+# https://github.com/tokio-rs/tokio/issues/2055.  Some of our tests
+# manage to not fit in the default 2MiB stack anymore due to this, so
+# while the issue is not resolved we want to work around this.
+# Because compiling optimised builds takes a very long time we prefer
+# to avoid that.  Setting this environment variable ensures that when
+# invoking `cargo test` threads are allowed to have a large enough
+# stack size without needing to use an optimised build.
 RUST_MIN_STACK = "8388608"
diff --git a/Cargo.toml b/Cargo.toml
index 82aa15e55..049c1225e 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -9,7 +9,6 @@ rust-version = "1.56"
 [profile.dev]
 debug = 0
 panic = 'abort'
-opt-level = 0
 
 [profile.release]
 lto = true