diff --git a/development/scons/scons_manifest.py b/development/scons/scons_manifest.py
index 3fec72119f..74ade016aa 100644
--- a/development/scons/scons_manifest.py
+++ b/development/scons/scons_manifest.py
@@ -454,14 +454,14 @@ src_frontends_header_files = Split('''
 
 
 src_frontends_files = Split('''
-    Alert.C
-    Application.C
-    Dialogs.C
-    LyXView.C
-    Painter.C
-    Timeout.C
-    Toolbars.C
-    WorkArea.C
+    Alert.cpp
+    Application.cpp
+    Dialogs.cpp
+    LyXView.cpp
+    Painter.cpp
+    Timeout.cpp
+    Toolbars.cpp
+    WorkArea.cpp
 ''')
 
 
diff --git a/po/POTFILES.in b/po/POTFILES.in
index 7ab43d7291..5c9343fce3 100644
--- a/po/POTFILES.in
+++ b/po/POTFILES.in
@@ -15,8 +15,8 @@ src/converter.C
 src/debug.C
 src/exporter.C
 src/format.C
-src/frontends/LyXView.C
-src/frontends/WorkArea.C
+src/frontends/LyXView.cpp
+src/frontends/WorkArea.cpp
 src/frontends/controllers/ControlAboutlyx.cpp
 src/frontends/controllers/ControlBibtex.cpp
 src/frontends/controllers/ControlBox.cpp
diff --git a/src/frontends/Alert.C b/src/frontends/Alert.C
index a339b8b015..4ac7f9a478 100644
--- a/src/frontends/Alert.C
+++ b/src/frontends/Alert.C
@@ -1,5 +1,5 @@
 /**
- * \file Alert.C
+ * \file Alert.cpp
  * This file is part of LyX, the document processor.
  * Licence details can be found in the file COPYING.
  *
diff --git a/src/frontends/Application.C b/src/frontends/Application.C
index 08f678f990..cd62f7982c 100644
--- a/src/frontends/Application.C
+++ b/src/frontends/Application.C
@@ -1,5 +1,5 @@
 /**
- * \file frontend/Application.C
+ * \file frontend/Application.cpp
  * This file is part of LyX, the document processor.
  * Licence details can be found in the file COPYING.
  *
diff --git a/src/frontends/Clipboard.h b/src/frontends/Clipboard.h
index 67ce307e52..3381475cbc 100644
--- a/src/frontends/Clipboard.h
+++ b/src/frontends/Clipboard.h
@@ -63,7 +63,7 @@ public:
 
 } // namespace frontend
 
-/// Implementation is in Application.C
+/// Implementation is in Application.cpp
 extern frontend::Clipboard & theClipboard();
 
 } // namespace lyx
diff --git a/src/frontends/FontLoader.h b/src/frontends/FontLoader.h
index bddf8afcda..f6b60043f6 100644
--- a/src/frontends/FontLoader.h
+++ b/src/frontends/FontLoader.h
@@ -42,7 +42,7 @@ public:
 
 } // namespace frontend
 
-/// Implementation is in Application.C
+/// Implementation is in Application.cpp
 extern frontend::FontLoader & theFontLoader();
 
 } // namespace lyx
diff --git a/src/frontends/FontMetrics.h b/src/frontends/FontMetrics.h
index cdad1946da..c8087ebb21 100644
--- a/src/frontends/FontMetrics.h
+++ b/src/frontends/FontMetrics.h
@@ -118,7 +118,7 @@ public:
 
 class LyXFont;
 
-/// Implementation is in Application.C
+/// Implementation is in Application.cpp
 frontend::FontMetrics const & theFontMetrics(LyXFont const & f);
 
 } // namespace lyx
diff --git a/src/frontends/LyXView.C b/src/frontends/LyXView.C
index 1ae358e20e..6d6c9fcb30 100644
--- a/src/frontends/LyXView.C
+++ b/src/frontends/LyXView.C
@@ -1,5 +1,5 @@
 /**
- * \file LyXView.C
+ * \file LyXView.cpp
  * This file is part of LyX, the document processor.
  * Licence details can be found in the file COPYING.
  *
diff --git a/src/frontends/Makefile.am b/src/frontends/Makefile.am
index 666f965305..791c4545f1 100644
--- a/src/frontends/Makefile.am
+++ b/src/frontends/Makefile.am
@@ -13,10 +13,10 @@ noinst_LTLIBRARIES = libfrontends.la
 AM_CPPFLAGS += $(PCH_FLAGS) -I$(srcdir)/..  $(BOOST_INCLUDES)
 
 libfrontends_la_SOURCES = \
-	Alert.C \
+	Alert.cpp \
 	Alert.h \
 	Alert_pimpl.h \
-	Application.C \
+	Application.cpp \
 	Application.h \
 	NoGuiFontLoader.h \
 	NoGuiFontMetrics.h \
@@ -27,19 +27,19 @@ libfrontends_la_SOURCES = \
 	FontMetrics.h \
 	LyXKeySym.h \
 	LyXKeySymFactory.h \
-	LyXView.C \
+	LyXView.cpp \
 	LyXView.h \
 	Menubar.h \
-	Painter.C \
+	Painter.cpp \
 	Painter.h \
-	Timeout.C \
+	Timeout.cpp \
 	Timeout.h \
-	Toolbars.C \
+	Toolbars.cpp \
 	Toolbars.h \
 	Clipboard.h \
 	Gui.h \
 	Selection.h \
-	WorkArea.C \
+	WorkArea.cpp \
 	WorkArea.h \
 	key_state.h \
 	mouse_state.h
diff --git a/src/frontends/Painter.C b/src/frontends/Painter.C
index 845106188a..2cba549793 100644
--- a/src/frontends/Painter.C
+++ b/src/frontends/Painter.C
@@ -1,5 +1,5 @@
 /**
- * \file Painter.C
+ * \file Painter.cpp
  * This file is part of LyX, the document processor.
  * Licence details can be found in the file COPYING.
  *
diff --git a/src/frontends/Selection.h b/src/frontends/Selection.h
index 569ea0272d..9f8af37f2d 100644
--- a/src/frontends/Selection.h
+++ b/src/frontends/Selection.h
@@ -67,7 +67,7 @@ public:
 
 } // namespace frontend
 
-/// Implementation is in Application.C
+/// Implementation is in Application.cpp
 extern frontend::Selection & theSelection();
 
 } // namespace lyx
diff --git a/src/frontends/Timeout.C b/src/frontends/Timeout.C
index 21d673ce1a..7ef659b3d9 100644
--- a/src/frontends/Timeout.C
+++ b/src/frontends/Timeout.C
@@ -1,5 +1,5 @@
 /**
- * \file Timeout.C
+ * \file Timeout.cpp
  * This file is part of LyX, the document processor.
  * Licence details can be found in the file COPYING.
  *
diff --git a/src/frontends/Toolbars.C b/src/frontends/Toolbars.C
index 9da8e1a4cf..fcf7e565c9 100644
--- a/src/frontends/Toolbars.C
+++ b/src/frontends/Toolbars.C
@@ -1,5 +1,5 @@
 /**
- * \file Toolbars.C
+ * \file Toolbars.cpp
  * This file is part of LyX, the document processor.
  * Licence details can be found in the file COPYING.
  *
diff --git a/src/frontends/WorkArea.C b/src/frontends/WorkArea.C
index c1a89e18a9..d6d2c93a26 100644
--- a/src/frontends/WorkArea.C
+++ b/src/frontends/WorkArea.C
@@ -1,5 +1,5 @@
 /**
- * \file WorkArea.C
+ * \file WorkArea.cpp
  * This file is part of LyX, the document processor.
  * Licence details can be found in the file COPYING.
  *