diff --git a/glxbackend.cpp b/glxbackend.cpp
index c59c647b1a..32fea4dd62 100644
--- a/glxbackend.cpp
+++ b/glxbackend.cpp
@@ -141,6 +141,9 @@ GlxBackend::~GlxBackend()
     if (window)
         XDestroyWindow(display(), window);
 
+    qDeleteAll(m_fbconfigHash);
+    m_fbconfigHash.clear();
+
     overlayWindow()->destroy();
     delete m_overlayWindow;
 }
@@ -446,12 +449,13 @@ int GlxBackend::visualDepth(xcb_visualid_t visual) const
 
 FBConfigInfo *GlxBackend::infoForVisual(xcb_visualid_t visual)
 {
-    FBConfigInfo *&info = m_fbconfigHash[visual];
+    auto it = m_fbconfigHash.constFind(visual);
+    if (it != m_fbconfigHash.constEnd()) {
+        return it.value();
+    }
 
-    if (info)
-        return info;
-
-    info = new FBConfigInfo;
+    FBConfigInfo *info = new FBConfigInfo;
+    m_fbconfigHash.insert(visual, info);
     info->fbconfig            = nullptr;
     info->bind_texture_format = 0;
     info->texture_targets     = 0;