diff --git a/stack.yaml b/stack.yaml
index a6957cdc9..0e2f243a3 100644
--- a/stack.yaml
+++ b/stack.yaml
@@ -23,4 +23,6 @@ extra-deps:
 - doctemplates-0.8.2
 ghc-options:
    "$locals": -fhide-source-paths -Wno-missing-home-modules
+   # needed to avoid access violation on windows:
+   HsYAML: -fexternal-interpreter
 resolver: lts-15.11