diff --git a/src/messaging/IMAPStore.cpp b/src/messaging/IMAPStore.cpp
index 0025e55d..8b8d9457 100644
--- a/src/messaging/IMAPStore.cpp
+++ b/src/messaging/IMAPStore.cpp
@@ -31,6 +31,8 @@ namespace vmime {
 namespace messaging {
 
 
+#ifndef VMIME_BUILDING_DOC
+
 //
 // IMAPauthenticator: private class used internally
 //
@@ -66,6 +68,8 @@ private:
 	mutable authenticationInfos* m_infos;
 };
 
+#endif // VMIME_BUILDING_DOC
+
 
 
 //