diff --git a/src/handlers.c b/src/handlers.c
index 238cf26f..b9677917 100644
--- a/src/handlers.c
+++ b/src/handlers.c
@@ -908,7 +908,7 @@ static void handle_client_message(xcb_client_message_event_t *event) {
             case _NET_WM_MOVERESIZE_MOVE:
                 floating_drag_window(con->parent, &fake);
                 break;
-            case _NET_WM_MOVERESIZE_SIZE_TOPLEFT... _NET_WM_MOVERESIZE_SIZE_LEFT:
+            case _NET_WM_MOVERESIZE_SIZE_TOPLEFT ... _NET_WM_MOVERESIZE_SIZE_LEFT:
                 floating_resize_window(con->parent, false, &fake);
                 break;
             default:
diff --git a/travis/check-formatting.sh b/travis/check-formatting.sh
index ff406bea..d232339c 100755
--- a/travis/check-formatting.sh
+++ b/travis/check-formatting.sh
@@ -3,4 +3,4 @@
 set -e
 set -x
 
-clang-format-3.8 -i $(find . -name "*.[ch]" | tr '\n' ' ') && git diff --exit-code || (echo 'Code was not formatted using clang-format!'; false)
+clang-format-4.0 -i $(find . -name "*.[ch]" | tr '\n' ' ') && git diff --exit-code || (echo 'Code was not formatted using clang-format!'; false)
diff --git a/travis/travis-base-386.Dockerfile b/travis/travis-base-386.Dockerfile
index ddb3874e..e6ad51f8 100644
--- a/travis/travis-base-386.Dockerfile
+++ b/travis/travis-base-386.Dockerfile
@@ -13,12 +13,12 @@ RUN echo 'APT::Acquire::Retries "5";' > /etc/apt/apt.conf.d/80retry
 # (3608 kB/s)). Hence, let’s stick with httpredir.debian.org (default) for now.
 
 # Install mk-build-deps (for installing the i3 build dependencies),
-# clang and clang-format-3.8 (for checking formatting and building with clang),
+# clang and clang-format-4.0 (for checking formatting and building with clang),
 # lintian (for checking spelling errors),
 RUN linux32 apt-get update && \
     DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends \
     dpkg-dev devscripts git equivs \
-    clang clang-format-3.8 \
+    clang clang-format-4.0 \
     lintian && \
     rm -rf /var/lib/apt/lists/*
 
diff --git a/travis/travis-base-ubuntu-386.Dockerfile b/travis/travis-base-ubuntu-386.Dockerfile
index 1014407a..82e5ca29 100644
--- a/travis/travis-base-ubuntu-386.Dockerfile
+++ b/travis/travis-base-ubuntu-386.Dockerfile
@@ -13,12 +13,12 @@ RUN echo 'APT::Acquire::Retries "5";' > /etc/apt/apt.conf.d/80retry
 # (3608 kB/s)). Hence, let’s stick with httpredir.debian.org (default) for now.
 
 # Install mk-build-deps (for installing the i3 build dependencies),
-# clang and clang-format-3.8 (for checking formatting and building with clang),
+# clang and clang-format-4.0 (for checking formatting and building with clang),
 # lintian (for checking spelling errors),
 RUN linux32 apt-get update && \
     DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends \
     dpkg-dev devscripts git equivs \
-    clang clang-format-3.8 \
+    clang clang-format-4.0 \
     lintian && \
     rm -rf /var/lib/apt/lists/*
 
diff --git a/travis/travis-base-ubuntu.Dockerfile b/travis/travis-base-ubuntu.Dockerfile
index 0b4ec206..05066ec8 100644
--- a/travis/travis-base-ubuntu.Dockerfile
+++ b/travis/travis-base-ubuntu.Dockerfile
@@ -13,13 +13,13 @@ RUN echo 'APT::Acquire::Retries "5";' > /etc/apt/apt.conf.d/80retry
 # (3608 kB/s)). Hence, let’s stick with httpredir.debian.org (default) for now.
 
 # Install mk-build-deps (for installing the i3 build dependencies),
-# clang and clang-format-3.8 (for checking formatting and building with clang),
+# clang and clang-format-4.0 (for checking formatting and building with clang),
 # lintian (for checking spelling errors),
 # test suite dependencies (for running tests)
 RUN apt-get update && \
     DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends \
     dpkg-dev devscripts git equivs \
-    clang clang-format-3.8 \
+    clang clang-format-4.0 \
     lintian && \
     rm -rf /var/lib/apt/lists/*
 
diff --git a/travis/travis-base.Dockerfile b/travis/travis-base.Dockerfile
index be3780d4..907002e8 100644
--- a/travis/travis-base.Dockerfile
+++ b/travis/travis-base.Dockerfile
@@ -11,13 +11,13 @@ RUN echo 'APT::Acquire::Retries "5";' > /etc/apt/apt.conf.d/80retry
 # (3608 kB/s)). Hence, let’s stick with httpredir.debian.org (default) for now.
 
 # Install mk-build-deps (for installing the i3 build dependencies),
-# clang and clang-format-3.8 (for checking formatting and building with clang),
+# clang and clang-format-4.0 (for checking formatting and building with clang),
 # lintian (for checking spelling errors),
 # test suite dependencies (for running tests)
 RUN apt-get update && \
     DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends \
     dpkg-dev devscripts git equivs \
-    clang clang-format-3.8 \
+    clang clang-format-4.0 \
     lintian \
     libmodule-install-perl libanyevent-perl libextutils-pkgconfig-perl xcb-proto cpanminus xvfb xserver-xephyr xauth libinline-perl libinline-c-perl libxml-simple-perl libmouse-perl libmousex-nativetraits-perl libextutils-depends-perl perl libtest-deep-perl libtest-exception-perl libxml-parser-perl libtest-simple-perl libtest-fatal-perl libdata-dump-perl libtest-differences-perl libxml-tokeparser-perl libipc-run-perl libxcb-xtest0-dev libx11-xcb-perl libjson-xs-perl x11-xserver-utils && \
     rm -rf /var/lib/apt/lists/*