diff --git a/src/tools/qdoc/config.cpp b/src/tools/qdoc/config.cpp
index c63dba7a017..8729bf387f8 100644
--- a/src/tools/qdoc/config.cpp
+++ b/src/tools/qdoc/config.cpp
@@ -286,7 +286,10 @@ QString Config::getOutputDir() const
         t = overrideOutputDir;
     if (!Generator::useOutputSubdirs()) {
         t = t.left(t.lastIndexOf('/'));
-        t += QLatin1Char('/') + getString("HTML.outputsubdir");
+        QString singleOutputSubdir = getString("HTML.outputsubdir");
+        if (singleOutputSubdir.isEmpty())
+            singleOutputSubdir = "html";
+        t += QLatin1Char('/') + singleOutputSubdir;
     }
     return t;
 }
diff --git a/src/tools/qdoc/main.cpp b/src/tools/qdoc/main.cpp
index e163246e847..912cdad7eb9 100644
--- a/src/tools/qdoc/main.cpp
+++ b/src/tools/qdoc/main.cpp
@@ -170,6 +170,8 @@ static void loadIndexFiles(Config& config)
     if (config.getBool(QString("HTML.nosubdirs"))) {
         noOutputSubdirs = true;
         singleOutputSubdir = config.getString("HTML.outputsubdir");
+        if (singleOutputSubdir.isEmpty())
+            singleOutputSubdir = "html";
     }
 
     // Allow modules and third-party application/libraries to link