diff --git a/scripts/grade-01.sh b/scripts/grade-01.sh
index 6505296..5579366 100755
--- a/scripts/grade-01.sh
+++ b/scripts/grade-01.sh
@@ -18,8 +18,7 @@ RUNNERS=(
 )
 
 # Lints.
-cargo fmt --check
-cargo clippy
+run_linters || exit 1
 
 # Executes test for each runner.
 for RUNNER in "${RUNNERS[@]}"; do
diff --git a/scripts/grade-02.sh b/scripts/grade-02.sh
index cc6ada1..570f0e4 100755
--- a/scripts/grade-02.sh
+++ b/scripts/grade-02.sh
@@ -18,8 +18,7 @@ RUNNERS=(
 )
 
 # Lints.
-cargo fmt --check
-cargo clippy
+run_linters || exit 1
 
 # Executes test for each runner.
 for RUNNER in "${RUNNERS[@]}"; do
diff --git a/scripts/grade-03.sh b/scripts/grade-03.sh
index 4223bcb..bce3607 100755
--- a/scripts/grade-03.sh
+++ b/scripts/grade-03.sh
@@ -18,8 +18,7 @@ RUNNERS=(
 )
 
 # Lints.
-cargo fmt --check
-cargo clippy
+run_linters || exit 1
 
 # Executes test for each runner.
 for RUNNER in "${RUNNERS[@]}"; do
diff --git a/scripts/grade-06.sh b/scripts/grade-06.sh
index 02ab6f0..d139dcb 100755
--- a/scripts/grade-06.sh
+++ b/scripts/grade-06.sh
@@ -18,8 +18,7 @@ RUNNERS=(
 )
 
 # Lints.
-cargo fmt --check
-cargo clippy
+run_linters || exit 1
 
 # Executes test for each runner.
 for RUNNER in "${RUNNERS[@]}"; do
diff --git a/scripts/grade-utils.sh b/scripts/grade-utils.sh
index 4bc2b1e..8244ee5 100755
--- a/scripts/grade-utils.sh
+++ b/scripts/grade-utils.sh
@@ -10,12 +10,12 @@
 rustup toolchain update stable nightly
 
 echo_err() {
-    echo -e "\033[0;31m\033[1m$@\033[0m" 1>&2
+    echo "$@" 1>&2
 }
 export -f echo_err
 
 # check_diff FILE TEST_LINES_FROM_TAIL
-# Abort if tests are modified.
+# Abort if "--lib" tests are modified.
 # Uses global variable TEMPLATE_REV.
 check_diff() {
     local FILE=$1
@@ -25,13 +25,26 @@ check_diff() {
 }
 export -f check_diff
 
+# Returns non-zero exit code if any of the linters have failed.
+run_linters() {
+    cargo fmt -- --check
+    local FMT_ERR=$?
+    cargo clippy -- -D warnings
+    local CLIPPY_ERR=$?
+    [ "$FMT_ERR" -ne 0 ] && echo_err 'Please format your code with `cargo fmt` first.'
+    [ "$CLIPPY_ERR" -ne 0 ] && echo_err 'Please fix the issues from `cargo clippy` first.'
+    return $(( FMT_ERR || CLIPPY_ERR ))
+}
+export -f run_linters
+
 # usage: cargo_asan [SUBCOMMAND] [OPTIONS] [-- <args>...]
 # example: cargo_asan test --release TEST_NAME -- --skip SKIPPED
+# NOTE: sanitizer documentation at https://doc.rust-lang.org/beta/unstable-book/compiler-flags/sanitizer.html
 cargo_asan() {
     local SUBCOMMAND=$1; shift
     RUSTFLAGS="-Z sanitizer=address" \
         RUSTDOCFLAGS="-Z sanitizer=address" \
-        cargo +nightly $SUBCOMMAND --target x86_64-unknown-linux-gnu $@
+        cargo +nightly $SUBCOMMAND -Z build-std --target x86_64-unknown-linux-gnu "$@"
 }
 export -f cargo_asan
 
@@ -41,24 +54,32 @@ cargo_tsan() {
         TSAN_OPTIONS="suppressions=suppress_tsan.txt" \
         RUSTDOCFLAGS="-Z sanitizer=thread" \
         RUST_TEST_THREADS=1 \
-        cargo +nightly $SUBCOMMAND --target x86_64-unknown-linux-gnu $@
+        cargo +nightly $SUBCOMMAND -Z build-std --target x86_64-unknown-linux-gnu "$@"
 }
 export -f cargo_tsan
 
 # usage: _run_tests_with CARGO [OPTIONS]
 # example: _run_tests_with cargo_tsan --release
-# echos number of failed tests
-# Uses global variable TESTS, TIMEOUT
-# [OPTIONS] must not contain " -- " (cargo options only)
+# Echos number of failed tests to stdout.
+# Echos error message to stderr.
+# Uses global variables TESTS, TIMEOUT.
+# [OPTIONS] must not contain " -- " (cargo options only).
 _run_tests_with() {
     local CARGO=$1; shift
-    $CARGO test --no-run $@ &>/dev/null \
-        || (echo_err "Build failed!"; exit 1)
+    local MSGS # https://mywiki.wooledge.org/BashPitfalls#local_var.3D.24.28cmd.29
+    MSGS=$($CARGO test --no-run "$@" 2>&1)
+    if [ $? -ne 0 ]; then
+        echo_err "Build failed! Error message:"
+        echo_err "${MSGS}"
+        echo_err "--------------------------------------------------------------------------------"
+        echo ${#TESTS[@]} # failed all tests
+        exit 1
+    fi
 
     local FAILED=0
     for TEST in "${TESTS[@]}"; do
-        local TEST_CMD="$CARGO test $@ $TEST"
-        timeout ${TIMEOUT:-10s} bash -c "$TEST_CMD 2>/dev/null" 1>&2
+        local TEST_CMD="$CARGO test $* $TEST"
+        timeout ${TIMEOUT:-20s} bash -c "$TEST_CMD 2>/dev/null" 1>&2
         case $? in
             0) ;;
             124) echo_err "Test timed out: $TEST_CMD"; FAILED=$((FAILED + 1));;
@@ -73,6 +94,6 @@ _run_tests_with() {
 run_tests() {
     # "cargo --release" should be split into "cargo" and "--release"
     local IFS=' '
-    echo $(_run_tests_with $RUNNER)
+    _run_tests_with $RUNNER
 }
 export -f run_tests