diff --git a/bin/run-tests.sh b/bin/run-tests.sh
index 204542d..b760867 100755
--- a/bin/run-tests.sh
+++ b/bin/run-tests.sh
@@ -22,26 +22,18 @@ for test_dir in tests/*; do
 
     bin/run.sh "${test_dir_name}" "${test_dir_path}" "${test_dir_path}"
 
-    # OPTIONAL: Normalize the results file
-    # If the results.json file contains information that changes between 
-    # different test runs (e.g. timing information or paths), you should normalize
-    # the results file to allow the diff comparison below to work as expected
-    # sed -i -E \
-    #   -e 's/Elapsed time: [0-9]+\.[0-9]+ seconds//g' \
-    #   -e "s~${test_dir_path}~/solution~g" \
-    #   "${results_file_path}"
-
     # Add trailing newlines. Ignore line numbers.
     for i in "${results_file_path}" "${expected_results_file_path}"; do
-        sed 's/:\d\+:/:NN:/g' "${i}" "${i}" > "${i}.cleaned"
+        sed \
+            -e 's/:[0-9]\{1,\}:/:NN:/g' \
+            -e '/^{"version": 3, "status": "error"/ s/"message": ".*"}$/"message": "<compiler output>"}/' \
+            "${i}" "${i}" > "${i}.cleaned"
     done
     echo "${test_dir_name}: comparing results.json to expected_results.json"
-    diff "${results_file_path}.cleaned" "${expected_results_file_path}.cleaned"
-    rm "${results_file_path}.cleaned" "${expected_results_file_path}.cleaned"
-
-    if [ $? -ne 0 ]; then
+    if ! diff "${results_file_path}.cleaned" "${expected_results_file_path}.cleaned"; then
         exit_code=1
     fi
+    rm "${results_file_path}.cleaned" "${expected_results_file_path}.cleaned"
 done
 
 exit ${exit_code}
diff --git a/bin/run.sh b/bin/run.sh
index 5db936b..b420940 100755
--- a/bin/run.sh
+++ b/bin/run.sh
@@ -29,7 +29,7 @@ compilation_errors_file_name="compilation-errors"
 test_output_file_name="test-output.xml"
 results_file="${output_dir}/results.json"
 binary_file="${build_dir}/${slug}"
-test_file_path="${build_dir}/${slug//-/_}_test.cpp"
+test_file_path="${build_dir}/$(echo "${slug}" | tr - _)_test.cpp"
 
 # Create the output directory if it doesn't exist
 mkdir -p "${output_dir}"
@@ -47,7 +47,7 @@ cmake -DEXERCISM_TEST_SUITE=1 -DEXERCISM_RUN_ALL_TESTS=1 .
 make 2> "${compilation_errors_file_name}"
 
 # In case of compilation errors the executable will not be created
-[[ -f "./${slug}" ]] && chmod +x "./${slug}" && "./${slug}" -r xml -o "${test_output_file_name}"
+[ -f "./${slug}" ] && chmod +x "./${slug}" && "./${slug}" -r xml -o "${test_output_file_name}"
 /opt/test-runner/bin/exercism_parser "${build_dir}/${test_output_file_name}" "${results_file}" "${build_dir}/${compilation_errors_file_name}" "${test_file_path}"
 
 cd -
diff --git a/include/helpers.h b/include/helpers.h
index c8924bb..6243fae 100644
--- a/include/helpers.h
+++ b/include/helpers.h
@@ -9,15 +9,15 @@
 // trim from start (in place)
 static inline void ltrim(std::string &s)
 {
-    s.erase(s.begin(), std::find_if(s.begin(), s.end(),
-                                    std::not1(std::ptr_fun<int, int>(std::isspace))));
+    s.erase(s.begin(), std::find_if(s.begin(), s.end(), [](unsigned char ch)
+                                    { return !std::isspace(ch); }));
 }
 
 // trim from end (in place)
 static inline void rtrim(std::string &s)
 {
-    s.erase(std::find_if(s.rbegin(), s.rend(),
-                         std::not1(std::ptr_fun<int, int>(std::isspace)))
+    s.erase(std::find_if(s.rbegin(), s.rend(), [](unsigned char ch)
+                         { return !std::isspace(ch); })
                 .base(),
             s.end());
 }