diff --git a/.travis.yml b/.travis.yml
index a1f736b..bc4e23c 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,10 +1,12 @@
 env:
+  global:
+    - CLANG_FORMAT_VERSION=9
   matrix:
     - JANSSON_BUILD_METHOD=cmake JANSSON_CMAKE_OPTIONS="-DJANSSON_TEST_WITH_VALGRIND=ON" JANSSON_EXTRA_INSTALL="valgrind"
     - JANSSON_BUILD_METHOD=autotools
     - JANSSON_BUILD_METHOD=coverage JANSSON_CMAKE_OPTIONS="-DJANSSON_COVERAGE=ON -DJANSSON_COVERALLS=ON -DCMAKE_BUILD_TYPE=Debug" JANSSON_EXTRA_INSTALL="lcov curl"
     - JANSSON_BUILD_METHOD=fuzzer
-    - JANSSON_BUILD_METHOD=lint
+    - JANSSON_BUILD_METHOD=lint CLANG_FORMAT=clang-format-9
 dist: bionic
 language: c
 compiler:
@@ -17,7 +19,7 @@ matrix:
     - compiler: clang
       env: JANSSON_BUILD_METHOD=fuzzer
     - compiler: gcc
-      env: JANSSON_BUILD_METHOD=lint
+      env: JANSSON_BUILD_METHOD=lint CLANG_FORMAT=clang-format-9
   allow_failures:
     - env: JANSSON_BUILD_METHOD=coverage JANSSON_CMAKE_OPTIONS="-DJANSSON_COVERAGE=ON -DJANSSON_COVERALLS=ON -DCMAKE_BUILD_TYPE=Debug" JANSSON_EXTRA_INSTALL="lcov curl"
 install:
@@ -29,4 +31,4 @@ script:
   - if [ "$JANSSON_BUILD_METHOD" = "cmake" ]; then mkdir build && cd build && cmake $JANSSON_CMAKE_OPTIONS .. && cmake --build . && ctest --output-on-failure; fi
   - if [ "$JANSSON_BUILD_METHOD" = "coverage" ]; then mkdir build && cd build && cmake $JANSSON_CMAKE_OPTIONS .. && cmake --build . && cmake --build . --target coveralls; fi
   - if [ "$JANSSON_BUILD_METHOD" = "fuzzer" ]; then ./test/ossfuzz/travisoss.sh; fi
-  - if [ "$JANSSON_BUILD_METHOD" = "lint" ]; then ./scripts/clang-format-check 9; fi
+  - if [ "$JANSSON_BUILD_METHOD" = "lint" ]; then ./scripts/clang-format-check; fi
diff --git a/scripts/clang-format-check b/scripts/clang-format-check
index f3f0f6d..983e55d 100755
--- a/scripts/clang-format-check
+++ b/scripts/clang-format-check
@@ -1,21 +1,19 @@
 #!/bin/bash
 
-clangformat="clang-format"
-if [ -n "$1" ]; then
-    clangformat="clang-format-$1"
-fi
+CLANG_FORMAT=${CLANG_FORMAT:-clang-format}
+CLANG_FORMAT_VERSION=${CLANG_FORMAT_VERSION:-}
 
-if ! type $clangformat >/dev/null; then
-    # clang-format not found. If running tests, mark this test as
-    # skipped.
+if ! type $CLANG_FORMAT >/dev/null || \
+        ! $CLANG_FORMAT --version | grep -q "version ${CLANG_FORMAT_VERSION}"; then
+    # If running tests, mark this test as skipped.
     exit 77
 fi
 
 errors=0
-paths=$(find . -type f -a '(' -name '*.c' -o -name '*.h' ')')
+paths=$(git ls-files | grep '\.[ch]$')
 for path in $paths; do
     in=$(cat $path)
-    out=$($clangformat $path)
+    out=$($CLANG_FORMAT $path)
 
     if [ "$in" != "$out" ]; then
         diff -u -L $path -L "$path.formatted" $path - <<<$out