diff --git a/doc/doxygen.cfg.in b/doc/doxygen.cfg.in
index 8132cd16..1a5dbf56 100644
--- a/doc/doxygen.cfg.in
+++ b/doc/doxygen.cfg.in
@@ -42,6 +42,7 @@ INPUT            = @top_srcdir@/doc/index.doxygen \
 		   @top_srcdir@/src/userfile.c \
 		   @top_srcdir@/src/control/cards.c \
 		   @top_srcdir@/src/control/control.c \
+		   @top_srcdir@/src/control/control_ext.c \
 		   @top_srcdir@/src/control/control_plugin.c \
 		   @top_srcdir@/src/control/control_hw.c \
 		   @top_srcdir@/src/control/control_remap.c \
diff --git a/src/control/control_ext.c b/src/control/control_ext.c
index 09106df1..cf3da3d8 100644
--- a/src/control/control_ext.c
+++ b/src/control/control_ext.c
@@ -622,7 +622,7 @@ The rest fields are filled by #snd_ctl_ext_create().  The handle field
 is the resultant PCM handle.  The others are the current status of the
 PCM.
 
-\section ctl_ext_impl Callback Functions of External Control Plugins
+\section ctl_ext_impl_cb Callback Functions of External Control Plugins
 
 The callback functions in #snd_ctl_ext_callback_t define the real
 behavior of the driver.  There are many callbacks but many of them are optional.