diff --git a/.travis.yml b/.travis.yml
index 2b8e3f0..5fb6a43 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -6,5 +6,5 @@ services:
 
 script:
   - docker build -t slirp4netns-tests -f Dockerfile.tests .
-  - docker run --security-opt seccomp="unconfined" -ti --rm -v /dev:/dev slirp4netns-tests
+  - docker run --security-opt seccomp="unconfined" --rm -v /dev:/dev slirp4netns-tests
   - docker build -q -f Dockerfile.buildtests .
diff --git a/Dockerfile.tests b/Dockerfile.tests
index 9f93f66..618c852 100644
--- a/Dockerfile.tests
+++ b/Dockerfile.tests
@@ -1,4 +1,4 @@
-FROM ubuntu AS build
+FROM ubuntu:18.04 AS build
 RUN apt update && apt install -y automake autotools-dev make gcc libglib2.0-dev
 COPY . /slirp4netns
 WORKDIR /slirp4netns
diff --git a/Makefile.am b/Makefile.am
index 2bf05ca..644e733 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -117,7 +117,7 @@ benchmark:
 
 ci:
 	$(MAKE) indent
-	test -z "$(git diff)"
+	git diff --exit-code
 # TODO: make sure ./vendor is synced with ./vendor.sh
 # (hard to verify during `make`, because vendor.sh removes ./vendor/libslirp/src/.deps)
 	$(MAKE) lint
diff --git a/main.c b/main.c
index 38ec167..3bdcac4 100644
--- a/main.c
+++ b/main.c
@@ -132,10 +132,8 @@ static int configure_network(const char *tapname,
     }
 
     // set loopback device to UP
-    struct ifreq ifr_lo = {
-	    .ifr_name = "lo",
-	    .ifr_flags = IFF_UP | IFF_RUNNING
-    };
+    struct ifreq ifr_lo = { .ifr_name = "lo",
+                            .ifr_flags = IFF_UP | IFF_RUNNING };
     if (ioctl(sockfd, SIOCSIFFLAGS, &ifr_lo) < 0) {
         perror("cannot set device up");
         return -1;