diff --git a/plugins/qmljs/duchain/cache.cpp b/plugins/qmljs/duchain/cache.cpp
--- a/plugins/qmljs/duchain/cache.cpp
+++ b/plugins/qmljs/duchain/cache.cpp
@@ -61,7 +61,7 @@
     QString cacheKey = uri + version;
     QString path = m_modulePaths.value(cacheKey, QString());
 
-    if (!path.isNull()) {
+    if (!path.isEmpty()) {
         return path;
     }
 
@@ -158,7 +158,7 @@
             dumpFile
         );
 
-        if (!dumpPath.isNull()) {
+        if (!dumpPath.isEmpty()) {
             QMutexLocker lock(&m_mutex);
 
             result.append(dumpPath);
diff --git a/plugins/qmljs/duchain/declarationbuilder.cpp b/plugins/qmljs/duchain/declarationbuilder.cpp
--- a/plugins/qmljs/duchain/declarationbuilder.cpp
+++ b/plugins/qmljs/duchain/declarationbuilder.cpp
@@ -712,7 +712,7 @@
         decl->setClassType(ClassDeclarationData::Interface);
         decl->clearBaseClasses();
 
-        if (!baseClass.isNull()) {
+        if (!baseClass.isEmpty()) {
             addBaseClass(decl, baseClass);
         }
 
@@ -731,7 +731,7 @@
     QString type_name = QmlJS::getQMLAttributeValue(node->members, QStringLiteral("type")).value;
     QmlJS::FunctionType::Ptr type(new QmlJS::FunctionType);
 
-    if (type_name.isNull()) {
+    if (type_name.isEmpty()) {
         type->setReturnType(typeFromName(QStringLiteral("void")));
     } else {
         type->setReturnType(typeFromName(type_name));
@@ -1082,7 +1082,7 @@
 {
     if (node->importUri) {
         importModule(node);
-    } else if (!node->fileName.isNull() && node->fileName != QLatin1String(".")) {
+    } else if (!node->fileName.isEmpty() && node->fileName != QLatin1String(".")) {
         QUrl currentFileUrl = currentContext()->topContext()->url().toUrl();
         QUrl importUrl = QUrl(node->fileName.toString());
 
diff --git a/plugins/qmljs/duchain/frameworks/nodejs.cpp b/plugins/qmljs/duchain/frameworks/nodejs.cpp
--- a/plugins/qmljs/duchain/frameworks/nodejs.cpp
+++ b/plugins/qmljs/duchain/frameworks/nodejs.cpp
@@ -190,7 +190,7 @@
     for (auto path : moduleDirectories(url)) {
         fileName = fileOrDirectoryPath(path.cd(moduleName).toLocalFile());
 
-        if (!fileName.isNull()) {
+        if (!fileName.isEmpty()) {
             break;
         }
     }
diff --git a/plugins/qmljs/duchain/helper.cpp b/plugins/qmljs/duchain/helper.cpp
--- a/plugins/qmljs/duchain/helper.cpp
+++ b/plugins/qmljs/duchain/helper.cpp
@@ -147,7 +147,7 @@
     // The expression must be an identifier or a string literal
     res.value = getNodeValue(statement->expression);
 
-    if (res.value.isNull()) {
+    if (res.value.isEmpty()) {
         return res;
     }