diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 063f957..1ceba90 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -25,7 +25,7 @@ jobs:
         with:
           otp-version: ${{matrix.otp}}
           rebar3-version: ${{matrix.rebar3}}
-      - run: rebar3 do eunit, ct --cover, cover
+      - run: DIAGNOSTIC=1 rebar3 do eunit, ct --cover, cover
 
   newer-builds:
     name: Newer Erlang/OTP ${{matrix.otp}}