diff --git a/Source/g_game.c b/Source/g_game.c
index 44d4f8eb..2d485a44 100644
--- a/Source/g_game.c
+++ b/Source/g_game.c
@@ -135,6 +135,8 @@ int     key_escape = KEYD_ESCAPE;                           // phares 4/13/98
 int     key_help = KEYD_F1;                                 // phares 4/13/98
 // [FG] double click acts as "use"
 int     dclick_use;
+// [FG] invert vertical axis
+int     mouse_y_invert;
 
 #define MAXPLMOVE   (forwardmove[1])
 #define TURBOTHRESHOLD  0x32
@@ -483,7 +485,7 @@ void G_BuildTiccmd(ticcmd_t* cmd)
   // [crispy] mouse look
   if (mouselook)
   {
-      cmd->lookdir = mousey;
+      cmd->lookdir = mouse_y_invert ? -mousey : mousey;
   }
   else if (!novert)
   {
diff --git a/Source/m_menu.c b/Source/m_menu.c
index 0fcb8245..130d2da1 100644
--- a/Source/m_menu.c
+++ b/Source/m_menu.c
@@ -3661,7 +3661,8 @@ setup_menu_t gen_settings1[] = { // General Settings screen1
 };
 
 enum {
-  general_mouse1
+  general_mouse1,
+  general_mouse2
 };
 
 enum {
@@ -3695,6 +3696,10 @@ setup_menu_t gen_settings2[] = { // General Settings screen2
   {"Double Click acts as \"Use\"", S_YESNO, m_null, G_X,
    G_Y + general_mouse1*8, {"dclick_use"}},
 
+  // [FG] invert vertical axis
+  {"Invert vertical axis", S_YESNO, m_null, G_X,
+   G_Y + general_mouse2*8, {"mouse_y_invert"}},
+
   {"Miscellaneous"  ,S_SKIP|S_TITLE, m_null, G_X, G_Y3 - 12},
 
   {"Maximum number of player corpses", S_NUM|S_PRGWARN, m_null, G_X,
diff --git a/Source/m_misc.c b/Source/m_misc.c
index e8fc75b7..21254839 100644
--- a/Source/m_misc.c
+++ b/Source/m_misc.c
@@ -67,6 +67,8 @@ static int config_help;         //jff 3/3/98
 int screenshot_pcx; //jff 3/30/98 // option to output screenshot as pcx or bmp
 // [FG] double click acts as "use"
 extern int dclick_use;
+// [FG] invert vertical axis
+extern int mouse_y_invert;
 extern int axis_forward;
 extern int axis_strafe;
 extern int axis_turn;
@@ -1296,6 +1298,14 @@ default_t defaults[] = {
     "double click acts as \"use\""
   },
 
+  // [FG] invert vertical axis
+  {
+    "mouse_y_invert",
+    (config_t *) &mouse_y_invert, NULL,
+    {0}, {0,1}, number, ss_gen, wad_no,
+    "invert vertical axis"
+  },
+
   { // killough
     "snd_channels",
     (config_t *) &default_numChannels, NULL,