diff --git a/Dockerfile b/Dockerfile
index 5631e3f..41a4981 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -7,10 +7,8 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
       unzip=6.0-28 \
     && rm -rf /var/lib/apt/lists/*
 
-RUN set -eux; \
-    if ! pecl list | grep -q xdebug; then \
-        pecl install xdebug-3.3.2 && docker-php-ext-enable xdebug; \
-    fi
+RUN bash -c '[[ -n "$(pecl list | grep xdebug)" ]]\
+ || (pecl install xdebug-3.3.2 && docker-php-ext-enable xdebug)'
 
 COPY --from=composer:latest /usr/bin/composer /usr/local/bin/composer