diff --git a/headers/os/app/Roster.h b/headers/os/app/Roster.h
index 6d2d20f7a9..d203d0cfac 100644
--- a/headers/os/app/Roster.h
+++ b/headers/os/app/Roster.h
@@ -13,6 +13,7 @@
 #include <Messenger.h>
 #include <OS.h>
 
+class BFile;
 class BMimeType;
 class BNodeInfo;
 
diff --git a/headers/os/mail/MailAttachment.h b/headers/os/mail/MailAttachment.h
index c970ebed9c..96c4bd2a24 100644
--- a/headers/os/mail/MailAttachment.h
+++ b/headers/os/mail/MailAttachment.h
@@ -11,6 +11,8 @@
 #include <MailContainer.h>
 #include <MailComponent.h>
 
+class BFile;
+
 class BMailAttachment : public BMailComponent {
 	public:
 		virtual void SetFileName(const char *name) = 0;
diff --git a/headers/os/media/MediaNode.h b/headers/os/media/MediaNode.h
index e3e70af953..59e9de8319 100644
--- a/headers/os/media/MediaNode.h
+++ b/headers/os/media/MediaNode.h
@@ -20,6 +20,7 @@
 #include <new>
 
 class BBufferConsumer;
+class BBufferProducer;
 class BControllable;
 class BFileInterface;
 class BMediaAddOn;
diff --git a/headers/os/media/Sound.h b/headers/os/media/Sound.h
index 6e8acf033a..819e9f08d4 100644
--- a/headers/os/media/Sound.h
+++ b/headers/os/media/Sound.h
@@ -8,6 +8,7 @@
 
 class BMediaFile;
 class BSoundFile;
+class BSoundPlayer;
 struct entry_ref;
 
 namespace BPrivate {
diff --git a/headers/os/storage/Directory.h b/headers/os/storage/Directory.h
index e1494cefdc..8fcb7fb90a 100644
--- a/headers/os/storage/Directory.h
+++ b/headers/os/storage/Directory.h
@@ -10,6 +10,7 @@
 #include <EntryList.h>
 #include <StorageDefs.h>
 
+class BFile;
 class BSymLink;
 
 
diff --git a/headers/os/storage/File.h b/headers/os/storage/File.h
index 8b3351ad76..80850b1954 100644
--- a/headers/os/storage/File.h
+++ b/headers/os/storage/File.h
@@ -10,6 +10,9 @@
 #include <Node.h>
 
 
+class BEntry;
+
+
 class BFile : public BNode, public BPositionIO {
 	public:
 		BFile();
diff --git a/headers/os/storage/Node.h b/headers/os/storage/Node.h
index e7467af732..a9f5ecb073 100644
--- a/headers/os/storage/Node.h
+++ b/headers/os/storage/Node.h
@@ -9,6 +9,7 @@
 #include <Statable.h>
 
 class BDirectory;
+class BEntry;
 class BString;
 struct entry_ref;
 
diff --git a/src/kits/tracker/FindPanel.h b/src/kits/tracker/FindPanel.h
index fe52ef489b..5aed8806cb 100644
--- a/src/kits/tracker/FindPanel.h
+++ b/src/kits/tracker/FindPanel.h
@@ -54,6 +54,7 @@ class BTextControl;
 class BCheckBox;
 class BMenuField;
 class BFile;
+class BPopUpMenu;
 
 namespace BPrivate {
 
diff --git a/src/kits/tracker/InfoWindow.h b/src/kits/tracker/InfoWindow.h
index 581a5eb191..b5d1df85bb 100644
--- a/src/kits/tracker/InfoWindow.h
+++ b/src/kits/tracker/InfoWindow.h
@@ -44,6 +44,7 @@ All rights reserved.
 #include "Utilities.h"
 
 
+class BFilePanel;
 class BMenuField;
 
 namespace BPrivate {