diff --git a/validate.sh b/validate.sh
index 40ad0576b5f..edb1db83277 100755
--- a/validate.sh
+++ b/validate.sh
@@ -329,7 +329,7 @@ CABALLISTBIN="${CABAL} list-bin --builddir=$BUILDDIR --project-file=$PROJECTFILE
 # of validate.sh
 # https://github.com/haskell/cabal/issues/9571
 # https://github.com/haskell/cabal/pull/10114
-RTSOPTS="$([[ $ARCH = "x86_64-windows" && -z "$CI" ]] && echo "+RTS --io-manager=native" || echo "")"
+RTSOPTS="$([ $ARCH = "x86_64-windows" ] &&  [ -z "$CI" ] && echo "+RTS --io-manager=native" || echo "")"
 
 # header
 #######################################################################