diff --git a/library/compiler-builtins/libm/.travis.yml b/library/compiler-builtins/libm/.travis.yml
index 0c0832793474..ae03b6601973 100644
--- a/library/compiler-builtins/libm/.travis.yml
+++ b/library/compiler-builtins/libm/.travis.yml
@@ -22,6 +22,8 @@ install:
   - bash ci/install.sh
 
 script:
+  # code must be already formatted
+  - cargo fmt -- --check
   - bash ci/script.sh
 
 after_script: set +e
diff --git a/library/compiler-builtins/libm/ci/install.sh b/library/compiler-builtins/libm/ci/install.sh
index efdbb06c206e..68dd0f337ac1 100644
--- a/library/compiler-builtins/libm/ci/install.sh
+++ b/library/compiler-builtins/libm/ci/install.sh
@@ -5,6 +5,8 @@ main() {
         cargo install cross
     fi
 
+    rustup component add rustfmt-preview
+
     rustup target add x86_64-unknown-linux-musl
 
     if [ $TARGET != x86_64-unknown-linux-gnu ]; then
diff --git a/library/compiler-builtins/libm/ci/script.sh b/library/compiler-builtins/libm/ci/script.sh
index 3db6bfeb12d9..d29003052508 100644
--- a/library/compiler-builtins/libm/ci/script.sh
+++ b/library/compiler-builtins/libm/ci/script.sh
@@ -10,10 +10,8 @@ main() {
     # generate tests
     cargo run --package test-generator --target x86_64-unknown-linux-musl
 
-    if cargo fmt --version >/dev/null 2>&1; then
-        # nicer syntax error messages (if any)
-        cargo fmt
-    fi
+    # nicer syntax error messages (if any)
+    cargo fmt
 
     # run tests
     cross test --target $TARGET --release