diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 502b08f2714daab0b77ab61e3c2f9e28b22347d9..739ffb4fab7b9f71ecb93450e7beb4d125c8c3a3 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -4,6 +4,13 @@ default:
   # Image from https://hub.docker.com/_/gcc/ based on Debian
   image: gcc
 
+whitespace:
+  stage: test
+  only:
+    - merge_requests
+  script:
+    - git diff-tree --check origin/master HEAD
+
 autoconf:
   stage: build
   before_script:
diff --git a/cmake/vla.c b/cmake/vla.c
index e83829e55455aab2e733612570d7c6d1687b9d9a..05b211979ed4799a7e28a6b430e815a48a97a04d 100644
--- a/cmake/vla.c
+++ b/cmake/vla.c
@@ -1,7 +1,7 @@
 int main() {
-    static int x; 
-    char a[++x]; 
-    a[sizeof a - 1] = 0; 
-    int N; 
+    static int x;
+    char a[++x];
+    a[sizeof a - 1] = 0;
+    int N;
     return a[0];
 }
\ No newline at end of file