diff --git a/entrypoint.sh b/entrypoint.sh
index f5c53ff..8ad3c0c 100755
--- a/entrypoint.sh
+++ b/entrypoint.sh
@@ -8,7 +8,7 @@ if [ -n "$NPM_AUTH_TOKEN" ]; then
   NPM_REGISTRY_URL="${NPM_REGISTRY_URL-registry.npmjs.org}"
 
   # Allow registry.npmjs.org to be overridden with an environment variable
-  printf "//$NPM_REGISTRY_URL/:_authToken=$NPM_AUTH_TOKEN\nregistry=$NPM_REGISTRY_URL" > "$NPM_CONFIG_USERCONFIG"
+  printf "//%s/:_authToken=%s\nregistry=%s" "$NPM_REGISTRY_URL" "$NPM_AUTH_TOKEN" "$NPM_REGISTRY_URL" > "$NPM_CONFIG_USERCONFIG"
   chmod 0600 "$NPM_CONFIG_USERCONFIG"
 fi