diff --git a/common/base64.c b/common/base64.c
index 3fc8a0c110..9ee2197fa0 100644
--- a/common/base64.c
+++ b/common/base64.c
@@ -54,7 +54,7 @@
 #ifdef PLATFORM_IS_ASCII
 #define CHARMAP_BASE 0x28
 #define E_IV E_INVALID  /* For table alignment */
-const unsigned char charmap[] =
+static const unsigned char charmap[] =
 {
     /* 0x28 */ E_IV, E_IV, E_IV, 0x3e, E_IV, E_IV, E_IV, 0x3f,
     /* 0x30 */ 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3b,
diff --git a/common/scancode.c b/common/scancode.c
index 2d48db5b77..cfe6a38608 100644
--- a/common/scancode.c
+++ b/common/scancode.c
@@ -311,7 +311,7 @@ enum settings_index
     SI_BASE
 };
 
-const struct map_settings global_settings[] =
+static const struct map_settings global_settings[] =
 {
     {
         // SI_EVDEV
@@ -328,7 +328,7 @@ const struct map_settings global_settings[] =
 };
 
 // Default mapping set is "evdev"
-const struct map_settings *settings = &global_settings[SI_EVDEV];
+static const struct map_settings *settings = &global_settings[SI_EVDEV];
 
 /*****************************************************************************/
 int
diff --git a/configure.ac b/configure.ac
index cc98d6d28e..3ac2311d8f 100644
--- a/configure.ac
+++ b/configure.ac
@@ -235,6 +235,7 @@ AX_APPEND_COMPILE_FLAGS([-Wextra])
 AX_APPEND_COMPILE_FLAGS([-Wno-missing-field-initializers])
 AX_APPEND_COMPILE_FLAGS([-Wno-unused-parameter])
 AX_APPEND_COMPILE_FLAGS([-Wno-sign-compare])
+AX_APPEND_COMPILE_FLAGS([-Wmissing-variable-declarations], ,[-Werror])
 
 AM_COND_IF([LINUX],
   [AX_APPEND_COMPILE_FLAGS([-Werror])]) # bsd has warnings that have not been fixed yet
diff --git a/sesman/chansrv/Makefile.am b/sesman/chansrv/Makefile.am
index e53961b440..c07fcfceef 100644
--- a/sesman/chansrv/Makefile.am
+++ b/sesman/chansrv/Makefile.am
@@ -74,6 +74,7 @@ xrdp_chansrv_SOURCES = \
   sound.h \
   xcommon.c \
   xcommon.h \
+  xcommon_x11.h \
   input.h \
   audin.c \
   audin.h
diff --git a/sesman/chansrv/audin.c b/sesman/chansrv/audin.c
index 2aa5ac0363..cb2f710053 100644
--- a/sesman/chansrv/audin.c
+++ b/sesman/chansrv/audin.c
@@ -33,6 +33,7 @@
 #include "xrdp_constants.h"
 #include "fifo.h"
 #include "audin.h"
+#include "sound.h"
 
 #define MSG_SNDIN_VERSION       1
 #define MSG_SNDIN_FORMATS       2
@@ -47,9 +48,6 @@
 #define AUDIN_NAME "AUDIO_INPUT"
 #define AUDIN_FLAGS  1 /* WTS_CHANNEL_OPTION_DYNAMIC */
 
-extern struct fifo *g_in_fifo; /* in sound.c */
-extern int g_bytes_in_fifo; /* in sound.c */
-
 struct xr_wave_format_ex
 {
     int wFormatTag;
diff --git a/sesman/chansrv/chansrv.c b/sesman/chansrv/chansrv.c
index c75c4f9e8a..5af9647f77 100644
--- a/sesman/chansrv/chansrv.c
+++ b/sesman/chansrv/chansrv.c
@@ -79,7 +79,7 @@ char *g_exec_name;
 tbus g_exec_event = 0;
 tbus g_exec_mutex;
 tbus g_exec_sem;
-int g_exec_pid = 0;
+static int g_exec_pid = 0;
 
 #define ARRAYSIZE(x) (sizeof(x)/sizeof(*(x)))
 /* max total channel bytes size */
diff --git a/sesman/chansrv/chansrv.h b/sesman/chansrv/chansrv.h
index 6e86f73799..8c3cd8041b 100644
--- a/sesman/chansrv/chansrv.h
+++ b/sesman/chansrv/chansrv.h
@@ -24,6 +24,19 @@
 #include "parse.h"
 #include "log.h"
 
+extern struct config_chansrv *g_cfg;
+
+extern int g_display_num;
+extern int g_cliprdr_chan_id;
+extern int g_rdpsnd_chan_id;
+extern int g_rdpdr_chan_id;
+extern int g_rail_chan_id;
+
+extern char *g_exec_name;
+extern tbus g_exec_event;
+extern tbus g_exec_mutex;
+extern tbus g_exec_sem;
+
 struct chan_item
 {
     int id;
diff --git a/sesman/chansrv/chansrv_fuse.c b/sesman/chansrv/chansrv_fuse.c
index 937a23eada..226f5e5137 100644
--- a/sesman/chansrv/chansrv_fuse.c
+++ b/sesman/chansrv/chansrv_fuse.c
@@ -16,18 +16,16 @@
  * limitations under the License.
  */
 
-/* FUSE mount point */
-char g_fuse_root_path[256] = "";
-#ifdef XRDP_FUSE
-static const char *g_fuse_root_path_basename; /* See xfuse_path_in_xfuse_fs() */
-static int g_fuse_root_parent_dev;   /* Ditto */
-static int g_fuse_root_parent_ino;   /* Ditto */
-#endif
-char g_fuse_clipboard_path[256] = ""; /* for clipboard use */
-
 #if defined(HAVE_CONFIG_H)
 #include <config_ac.h>
 #endif
+#include "arch.h"
+#include "chansrv_fuse.h"
+#include "chansrv_xfs.h"
+
+
+// Globals needed regardless of the value of XRDP_FUSE
+char g_fuse_clipboard_path[256] = ""; /* for clipboard use */
 
 #ifndef XRDP_FUSE
 
@@ -41,10 +39,6 @@ char g_fuse_clipboard_path[256] = ""; /* for clipboard use */
 #include <stdlib.h>
 #include <string.h>
 
-#include "arch.h"
-#include "chansrv_fuse.h"
-#include "chansrv_xfs.h"
-
 /* dummy calls when XRDP_FUSE is not defined */
 int xfuse_init(void)
 {
@@ -162,18 +156,21 @@ int xfuse_path_in_xfuse_fs(const char *path)
 #include <pthread.h>
 #include <sched.h>
 
-#include "arch.h"
 #include "os_calls.h"
 #include "string_calls.h"
 #include "clipboard_file.h"
-#include "chansrv_fuse.h"
-#include "chansrv_xfs.h"
 #include "chansrv.h"
 #include "chansrv_config.h"
 #include "devredir.h"
 #include "list.h"
 #include "file.h"
 
+/* FUSE mount point */
+static char g_fuse_root_path[256] = "";
+static const char *g_fuse_root_path_basename; /* See xfuse_path_in_xfuse_fs() */
+static int g_fuse_root_parent_dev;   /* Ditto */
+static int g_fuse_root_parent_ino;   /* Ditto */
+
 /* Check for FUSE features we may wish to use
  *
  * Note that FUSE_VERSION might be more useful for some features than
@@ -191,9 +188,6 @@ int xfuse_path_in_xfuse_fs(const char *path)
 #define XFUSE_ENTRY_TIMEOUT     5.0
 
 
-extern struct config_chansrv *g_cfg; /* in chansrv.c */
-
-
 /* Local utility functions */
 
 static inline char *
diff --git a/sesman/chansrv/chansrv_fuse.h b/sesman/chansrv/chansrv_fuse.h
index ae38356633..754d512fa8 100644
--- a/sesman/chansrv/chansrv_fuse.h
+++ b/sesman/chansrv/chansrv_fuse.h
@@ -25,6 +25,8 @@
 #include "arch.h"
 #include "ms-erref.h"
 
+extern char g_fuse_clipboard_path[256];
+
 /* Used to pass file info back to chansrv_fuse from devredir */
 struct file_attr
 {
diff --git a/sesman/chansrv/clipboard.c b/sesman/chansrv/clipboard.c
index f2fa792c2f..9616576be6 100644
--- a/sesman/chansrv/clipboard.c
+++ b/sesman/chansrv/clipboard.c
@@ -184,16 +184,8 @@ x-special/gnome-copied-files
 #define BMPFILEHEADER_LEN       14
 #define BMPINFOHEADER_LEN       40
 
-extern int g_cliprdr_chan_id;   /* in chansrv.c */
-
 extern Display *g_display;      /* in xcommon.c */
-extern int g_x_socket;          /* in xcommon.c */
-extern tbus g_x_wait_obj;       /* in xcommon.c */
 extern Screen *g_screen;        /* in xcommon.c */
-extern int g_screen_num;        /* in xcommon.c */
-
-extern struct config_chansrv *g_cfg; /* in chansrv.c */
-
 int g_clip_up = 0;
 
 static Atom g_clipboard_atom = 0;      /* CLIPBOARD */
diff --git a/sesman/chansrv/clipboard.h b/sesman/chansrv/clipboard.h
index 62108eb314..2afef9b651 100644
--- a/sesman/chansrv/clipboard.h
+++ b/sesman/chansrv/clipboard.h
@@ -23,6 +23,11 @@
 #include "arch.h"
 #include "parse.h"
 
+extern int g_clip_up;
+
+extern struct clip_s2c g_clip_s2c;
+extern struct clip_c2s g_clip_c2s;
+
 int clipboard_init(void);
 int clipboard_deinit(void);
 int clipboard_data_in(struct stream *s, int chan_id, int chan_flags, int length, int total_length);
diff --git a/sesman/chansrv/clipboard_file.c b/sesman/chansrv/clipboard_file.c
index 0be2f6e68e..e92c5284d3 100644
--- a/sesman/chansrv/clipboard_file.c
+++ b/sesman/chansrv/clipboard_file.c
@@ -44,13 +44,6 @@
 #include "chansrv_fuse.h"
 #include "ms-rdpeclip.h"
 
-extern int g_cliprdr_chan_id; /* in chansrv.c */
-
-extern struct clip_s2c g_clip_s2c; /* in clipboard.c */
-extern struct clip_c2s g_clip_c2s; /* in clipboard.c */
-
-extern char g_fuse_clipboard_path[];
-
 struct cb_file_info
 {
     char *pathname;
diff --git a/sesman/chansrv/devredir.c b/sesman/chansrv/devredir.c
index 85574e0df7..adda7cc764 100644
--- a/sesman/chansrv/devredir.c
+++ b/sesman/chansrv/devredir.c
@@ -100,9 +100,6 @@ enum COMPLETION_TYPE
 };
 
 
-/* globals */
-extern int g_rdpdr_chan_id; /* in chansrv.c */
-
 /* Capabilities from GENERAL_CAPS_SET in Client Core Capability Response */
 struct client_caps
 {
@@ -118,10 +115,10 @@ static struct client_caps g_ccap;
 
 tui32 g_completion_id = 1;
 
-tui32 g_clientID;           /* unique client ID - announced by client */
-tui32 g_device_id;          /* unique device ID - announced by client */
-tui16 g_client_rdp_version; /* returned by client                     */
-struct stream *g_input_stream = NULL;
+static tui32 g_clientID;           /* unique client ID - announced by client */
+static tui32 g_device_id;          /* unique device ID - announced by client */
+static tui16 g_client_rdp_version; /* returned by client                     */
+static struct stream *g_input_stream = NULL;
 
 /*
  * Local functions called from devredir_proc_device_iocompletion()
diff --git a/sesman/chansrv/devredir.h b/sesman/chansrv/devredir.h
index 651cb2a3d2..fc8e2670fa 100644
--- a/sesman/chansrv/devredir.h
+++ b/sesman/chansrv/devredir.h
@@ -24,6 +24,8 @@
 #include "irp.h"
 #include "ms-rdpefs.h"
 
+extern tui32 g_completion_id;
+
 int devredir_init(void);
 int devredir_deinit(void);
 
diff --git a/sesman/chansrv/irp.c b/sesman/chansrv/irp.c
index a1bf9a4d57..05ec52eb48 100644
--- a/sesman/chansrv/irp.c
+++ b/sesman/chansrv/irp.c
@@ -31,7 +31,7 @@
 #include "string_calls.h"
 #include "irp.h"
 
-IRP *g_irp_head = NULL;
+static IRP *g_irp_head = NULL;
 
 /**
  * Create a new IRP and append to linked list
diff --git a/sesman/chansrv/rail.c b/sesman/chansrv/rail.c
index a9bac1a6ff..a3adb02b7d 100644
--- a/sesman/chansrv/rail.c
+++ b/sesman/chansrv/rail.c
@@ -37,28 +37,13 @@
 #include "chansrv.h"
 #include "rail.h"
 #include "xcommon.h"
+#include "xcommon_x11.h"
 #include "log.h"
 #include "os_calls.h"
 #include "string_calls.h"
 #include "thread_calls.h"
 #include "list.h"
 
-extern int g_rail_chan_id;      /* in chansrv.c */
-extern int g_display_num;       /* in chansrv.c */
-extern char *g_exec_name;       /* in chansrv.c */
-extern tbus g_exec_event;       /* in chansrv.c */
-extern tbus g_exec_mutex;       /* in chansrv.c */
-extern tbus g_exec_sem;         /* in chansrv.c */
-
-extern Display *g_display;           /* in xcommon.c */
-extern Screen *g_screen;             /* in xcommon.c */
-extern Window g_root_window;         /* in xcommon.c */
-extern Atom g_wm_delete_window_atom; /* in xcommon.c */
-extern Atom g_wm_protocols_atom;     /* in xcommon.c */
-extern Atom g_utf8_string;           /* in xcommon.c */
-extern Atom g_net_wm_name;           /* in xcommon.c */
-extern Atom g_wm_state;              /* in xcommon.c */
-
 static Atom g_rwd_atom = 0;
 
 int g_rail_up = 0;
diff --git a/sesman/chansrv/rail.h b/sesman/chansrv/rail.h
index 74dcd20b6b..df26ea88bf 100644
--- a/sesman/chansrv/rail.h
+++ b/sesman/chansrv/rail.h
@@ -23,6 +23,8 @@
 #include "arch.h"
 #include "parse.h"
 
+extern int g_rail_up;
+
 int
 rail_init(void);
 int
diff --git a/sesman/chansrv/smartcard.c b/sesman/chansrv/smartcard.c
index 7dd1edd210..c35a9352aa 100644
--- a/sesman/chansrv/smartcard.c
+++ b/sesman/chansrv/smartcard.c
@@ -124,15 +124,11 @@ typedef struct smartcard
 } SMARTCARD;
 
 /* globals */
-SMARTCARD   *smartcards[MAX_SMARTCARDS];
-int          g_smartcards_inited = 0;
+static SMARTCARD   *smartcards[MAX_SMARTCARDS];
+static int          g_smartcards_inited = 0;
 static tui32 g_device_id = 0;
 static int   g_scard_index = 0;
 
-/* externs */
-extern tui32 g_completion_id;
-extern int   g_rdpdr_chan_id;    /* in chansrv.c */
-
 
 /******************************************************************************
 **                   static functions local to this file                     **
diff --git a/sesman/chansrv/smartcard_pcsc.c b/sesman/chansrv/smartcard_pcsc.c
index 0584188141..d459ac4916 100644
--- a/sesman/chansrv/smartcard_pcsc.c
+++ b/sesman/chansrv/smartcard_pcsc.c
@@ -56,8 +56,6 @@
 #if PCSC_STANDIN
 
 
-extern int g_display_num; /* in chansrv.c */
-
 static int g_autoinc = 0; /* general purpose autoinc */
 
 struct pcsc_card /* item for list of open cards in one context */
diff --git a/sesman/chansrv/sound.c b/sesman/chansrv/sound.c
index a67628b775..85c934eec1 100644
--- a/sesman/chansrv/sound.c
+++ b/sesman/chansrv/sound.c
@@ -62,10 +62,6 @@ static OpusEncoder *g_opus_encoder = 0;
 static lame_global_flags *g_lame_encoder = 0;
 #endif
 
-extern int g_rdpsnd_chan_id;    /* in chansrv.c */
-extern int g_display_num;       /* in chansrv.c */
-extern struct config_chansrv *g_cfg; /* in chansrv.c */
-
 /* audio out: sound_server -> xrdp -> NeutrinoRDP */
 static struct trans *g_audio_l_trans_out = 0; /* listener */
 static struct trans *g_audio_c_trans_out = 0; /* connection */
diff --git a/sesman/chansrv/sound.h b/sesman/chansrv/sound.h
index 2b846a95d0..188551d2e5 100644
--- a/sesman/chansrv/sound.h
+++ b/sesman/chansrv/sound.h
@@ -25,6 +25,9 @@
 #include "chansrv.h"
 #include "trans.h"
 
+extern struct fifo *g_in_fifo;
+extern int g_bytes_in_fifo;
+
 #define SNDC_CLOSE          0x01
 #define SNDC_WAVE           0x02
 #define SNDC_SETVOLUME      0x03
diff --git a/sesman/chansrv/xcommon.c b/sesman/chansrv/xcommon.c
index 2067bbd6f4..ec2660deb2 100644
--- a/sesman/chansrv/xcommon.c
+++ b/sesman/chansrv/xcommon.c
@@ -29,23 +29,23 @@
 #include "clipboard.h"
 #include "rail.h"
 #include "xcommon.h"
+#include "xcommon_x11.h"
 
-extern int g_clip_up;                         /* in clipboard.c */
-
-extern int g_rail_up;                         /* in rail.c */
-
+/* globals declared in xcommon_x11.h */
 Display *g_display = 0;
-int g_x_socket = 0;
-tbus g_x_wait_obj = 0;
 Screen *g_screen = 0;
 int g_screen_num = 0;
-Window g_root_window = 0;
 Atom g_wm_delete_window_atom = 0;
 Atom g_wm_protocols_atom = 0;
 Atom g_utf8_string = 0;
 Atom g_net_wm_name = 0;
 Atom g_wm_state = 0;
 
+/* globals declared in xcommon.h */
+int g_x_socket = 0;
+tbus g_x_wait_obj = 0;
+Window g_root_window = 0;
+
 static x_server_fatal_cb_type x_server_fatal_handler = 0;
 
 
diff --git a/sesman/chansrv/xcommon.h b/sesman/chansrv/xcommon.h
index 3195eda2a9..3351a45b3d 100644
--- a/sesman/chansrv/xcommon.h
+++ b/sesman/chansrv/xcommon.h
@@ -28,6 +28,15 @@
 
 typedef void (*x_server_fatal_cb_type)(void);
 
+/*
+ * Global variables defined in xcommon.c
+ *
+ * For globals with X11-specific types, see xcommon_x11.h
+ */
+extern int g_x_socket;
+extern tbus g_x_wait_obj;
+extern int g_screen_num;
+
 int
 xcommon_init(void);
 int
diff --git a/sesman/chansrv/xcommon_x11.h b/sesman/chansrv/xcommon_x11.h
new file mode 100644
index 0000000000..133842b0d2
--- /dev/null
+++ b/sesman/chansrv/xcommon_x11.h
@@ -0,0 +1,40 @@
+/**
+ * xrdp: A Remote Desktop Protocol server.
+ *
+ * Copyright (C) Jay Sorg 2012
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * @file sesman/chansrv/xcommon_vars.c
+ *
+ * xcommon global variables
+ *
+ * Declares global variables defined in xcommon.h with X11-specific types
+ */
+#if !defined(XCOMMON_X11_H)
+#define XCOMMON_X11_H
+
+#include <X11/Xlib.h>
+
+extern Display *g_display;
+extern Screen *g_screen;
+extern Window g_root_window;
+extern Atom g_wm_delete_window_atom;
+extern Atom g_wm_protocols_atom;
+extern Atom g_utf8_string;
+extern Atom g_net_wm_name;
+extern Atom g_wm_state;
+
+#endif
diff --git a/sesman/tools/sesadmin.c b/sesman/tools/sesadmin.c
index 18e02335b9..124114b8bd 100644
--- a/sesman/tools/sesadmin.c
+++ b/sesman/tools/sesadmin.c
@@ -34,8 +34,8 @@
 #include <unistd.h>
 
 
-char cmnd[257];
-char port[257];
+static char cmnd[257];
+static char port[257];
 
 static int cmndList(struct trans *t);
 static int cmndKill(struct trans *t);
diff --git a/sesman/tools/xcon.c b/sesman/tools/xcon.c
index a16f6e5a55..aceab0dca2 100644
--- a/sesman/tools/xcon.c
+++ b/sesman/tools/xcon.c
@@ -29,8 +29,8 @@
 #include <X11/Xlib.h>
 #include <sys/select.h>
 
-Display *g_display = 0;
-int g_x_socket = 0;
+static Display *g_display = 0;
+static int g_x_socket = 0;
 
 int main(int argc, char **argv)
 {
diff --git a/tests/libxrdp/test_xrdp_sec_process_mcs_data_monitors.c b/tests/libxrdp/test_xrdp_sec_process_mcs_data_monitors.c
index 27d8342227..2d1a2d449e 100644
--- a/tests/libxrdp/test_xrdp_sec_process_mcs_data_monitors.c
+++ b/tests/libxrdp/test_xrdp_sec_process_mcs_data_monitors.c
@@ -7,9 +7,9 @@
 
 #include "test_libxrdp.h"
 
-struct xrdp_sec *sec_layer;
-struct xrdp_rdp *rdp_layer;
-struct xrdp_session *session;
+static struct xrdp_sec *sec_layer;
+static struct xrdp_rdp *rdp_layer;
+static struct xrdp_session *session;
 
 static void setup(void)
 {
diff --git a/third_party/copying_third_party.h b/third_party/copying_third_party.h
index 1285dbaa6d..b60bff8b90 100644
--- a/third_party/copying_third_party.h
+++ b/third_party/copying_third_party.h
@@ -1,5 +1,5 @@
 #include <stdlib.h>
-const char copying_third_party[] = "\
+static const char copying_third_party[] = "\
 -- tomlc99: TOML C library\n\
 \n\
 MIT License\n\
@@ -27,4 +27,4 @@ SOFTWARE.\n\
 \n\
 --------------------------------------------------------------------------------\n\
 ";
-const size_t copying_third_party_len = sizeof(copying_third_party) - 1;
+static const size_t copying_third_party_len = sizeof(copying_third_party) - 1;
diff --git a/tools/devel/tcp_proxy/main.c b/tools/devel/tcp_proxy/main.c
index 9d1c7f38cd..3976b861f2 100644
--- a/tools/devel/tcp_proxy/main.c
+++ b/tools/devel/tcp_proxy/main.c
@@ -39,8 +39,8 @@
 #include "os_calls.h"
 #include "string_calls.h"
 
-int  g_loc_io_count = 0;  // bytes read from local port
-int  g_rem_io_count = 0;  // bytes read from remote port
+static int g_loc_io_count = 0;  // bytes read from local port
+static int g_rem_io_count = 0;  // bytes read from remote port
 
 static int g_terminated = 0;
 
diff --git a/xrdp/lang.c b/xrdp/lang.c
index a5ef2f476c..fb7562c935 100644
--- a/xrdp/lang.c
+++ b/xrdp/lang.c
@@ -46,7 +46,7 @@ struct km_general
     int caps_lock_supported;
 };
 
-const struct km_general km_general_default =
+static const struct km_general km_general_default =
 {
     .version = 0,
     .caps_lock_supported = 1
diff --git a/xrdp_accel_assist/xrdp_accel_assist_x11.c b/xrdp_accel_assist/xrdp_accel_assist_x11.c
index 3c1b41f4a9..020cd135cc 100644
--- a/xrdp_accel_assist/xrdp_accel_assist_x11.c
+++ b/xrdp_accel_assist/xrdp_accel_assist_x11.c
@@ -59,7 +59,7 @@
 
 /* X11 */
 Display *g_display = NULL;
-static int g_x_socket = 0;
+int g_x_socket = 0;
 int g_screen_num = 0;
 static Screen *g_screen = NULL;
 Window g_root_window = None;