diff --git a/lib/appenders/dateFile.js b/lib/appenders/dateFile.js
index 3f1ffc4..8999c74 100644
--- a/lib/appenders/dateFile.js
+++ b/lib/appenders/dateFile.js
@@ -10,7 +10,7 @@ function openTheStream(filename, pattern, options) {
     options
   );
   stream.on('error', (err) => {
-    console.error('log4js.dateFileAppender - Writing to file %s, error happened ', filename, err); //eslint-disable-line
+    console.error('log4js.dateFileAppender - Writing to file %s, error happened ', filename, err); // eslint-disable-line
   });
   stream.on("drain", () => {
     process.emit("log4js:pause", false);
diff --git a/lib/appenders/file.js b/lib/appenders/file.js
index e976a29..aeccddb 100644
--- a/lib/appenders/file.js
+++ b/lib/appenders/file.js
@@ -21,7 +21,7 @@ function openTheStream(file, fileSize, numFiles, options) {
     options
   );
   stream.on('error', (err) => {
-    console.error('log4js.fileAppender - Writing to file %s, error happened ', file, err); //eslint-disable-line
+    console.error('log4js.fileAppender - Writing to file %s, error happened ', file, err); // eslint-disable-line
   });
   stream.on('drain', () => {
     process.emit("log4js:pause", false);
diff --git a/lib/appenders/index.js b/lib/appenders/index.js
index db6a8b0..58b10c1 100644
--- a/lib/appenders/index.js
+++ b/lib/appenders/index.js
@@ -24,7 +24,7 @@ const appenders = new Map();
 const tryLoading = (modulePath, config) => {
   debug('Loading module from ', modulePath);
   try {
-    return require(modulePath); //eslint-disable-line
+    return require(modulePath); // eslint-disable-line
   } catch (e) {
     // if the module was found, and we still got an error, then raise it
     configuration.throwExceptionIf(
@@ -39,7 +39,7 @@ const tryLoading = (modulePath, config) => {
 const loadAppenderModule = (type, config) => coreAppenders.get(type)
   || tryLoading(`./${type}`, config)
   || tryLoading(type, config)
-  || (require.main && tryLoading(path.join(path.dirname(require.main.filename), type), config))
+  || (require.main && require.main.filename && tryLoading(path.join(path.dirname(require.main.filename), type), config))
   || tryLoading(path.join(process.cwd(), type), config);
 
 const appendersLoading = new Set();
diff --git a/lib/appenders/logLevelFilter.js b/lib/appenders/logLevelFilter.js
index 7c9012c..253fedd 100644
--- a/lib/appenders/logLevelFilter.js
+++ b/lib/appenders/logLevelFilter.js
@@ -3,7 +3,7 @@ function logLevelFilter(minLevelString, maxLevelString, appender, levels) {
   const maxLevel = levels.getLevel(maxLevelString, levels.FATAL);
   return (logEvent) => {
     const eventLevel = logEvent.level;
-    if (eventLevel.isGreaterThanOrEqualTo(minLevel) && eventLevel.isLessThanOrEqualTo(maxLevel)) {
+    if (minLevel.isLessThanOrEqualTo(eventLevel) && maxLevel.isGreaterThanOrEqualTo(eventLevel)) {
       appender(logEvent);
     }
   };