diff --git a/src/ci/scripts/install-ninja.sh b/src/ci/scripts/install-ninja.sh
index 7ac19173923cf..2427d23b18737 100755
--- a/src/ci/scripts/install-ninja.sh
+++ b/src/ci/scripts/install-ninja.sh
@@ -6,9 +6,13 @@ IFS=$'\n\t'
 
 source "$(cd "$(dirname "$0")" && pwd)/../shared.sh"
 
+# Check and set default values for variables
+: "${MIRRORS_BASE:?MIRRORS_BASE is not set}"
+: "${RUST_CONFIGURE_ARGS:=}"
+
 if isWindows; then
-    mkdir ninja
-    curl -o ninja.zip "${MIRRORS_BASE}/2024-03-28-v1.11.1-ninja-win.zip"
+    mkdir -p ninja
+    curl -fLo ninja.zip "${MIRRORS_BASE}/2024-03-28-v1.11.1-ninja-win.zip"
     7z x -oninja ninja.zip
     rm ninja.zip
     ciCommandSetEnv "RUST_CONFIGURE_ARGS" "${RUST_CONFIGURE_ARGS} --enable-ninja"