diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 56781596e29adba3d02a5523fd51a9ff45831344..5b1510f35373a034e5d7f4fe3c328e37ea95aa9a 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -6,6 +6,7 @@ stages:
 variables:
   CPU_CORES: "10"
   OCAML: "ocaml-variants.4.14.0+options ocaml-option-flambda"
+  NIGHTLY_COQ: "8.17.dev" # 8.18.dev causes an anomaly
 
 .template: &template
   stage: build