diff --git a/scripts/gen_keys.py b/scripts/gen_keys.py
index 6a275468e..51a659d73 100644
--- a/scripts/gen_keys.py
+++ b/scripts/gen_keys.py
@@ -36,6 +36,7 @@ print >>f, "\tKEY_MOUSE_7 = %d,"%(highestid+7); keynames[highestid+7] = "mouse7"
 print >>f, "\tKEY_MOUSE_8 = %d,"%(highestid+8); keynames[highestid+8] = "mouse8"
 print >>f, "\tKEY_MOUSE_WHEEL_UP = %d,"%(highestid+9); keynames[highestid+9] = "mousewheelup"
 print >>f, "\tKEY_MOUSE_WHEEL_DOWN = %d,"%(highestid+10); keynames[highestid+10] = "mousewheeldown"
+print >>f, "\tKEY_MOUSE_9 = %d,"%(highestid+11); keynames[highestid+11] = "mouse9"
 print >>f, "\tKEY_LAST,"
 
 print >>f, "};"
diff --git a/src/engine/client/input.cpp b/src/engine/client/input.cpp
index 7ff8d6fe2..972ebdf09 100644
--- a/src/engine/client/input.cpp
+++ b/src/engine/client/input.cpp
@@ -144,6 +144,7 @@ int CInput::Update()
 	if(i&SDL_BUTTON(6)) m_aInputState[m_InputCurrent][KEY_MOUSE_6] = 1;
 	if(i&SDL_BUTTON(7)) m_aInputState[m_InputCurrent][KEY_MOUSE_7] = 1;
 	if(i&SDL_BUTTON(8)) m_aInputState[m_InputCurrent][KEY_MOUSE_8] = 1;
+	if(i&SDL_BUTTON(9)) m_aInputState[m_InputCurrent][KEY_MOUSE_9] = 1;
 
 	{
 		SDL_Event Event;
@@ -186,6 +187,7 @@ int CInput::Update()
 					if(Event.button.button == 6) Key = KEY_MOUSE_6; // ignore_convention
 					if(Event.button.button == 7) Key = KEY_MOUSE_7; // ignore_convention
 					if(Event.button.button == 8) Key = KEY_MOUSE_8; // ignore_convention
+					if(Event.button.button == 9) Key = KEY_MOUSE_9; // ignore_convention
 					break;
 
 				// other messages
diff --git a/src/engine/client/keynames.h b/src/engine/client/keynames.h
index 7f790abe8..538f17431 100644
--- a/src/engine/client/keynames.h
+++ b/src/engine/client/keynames.h
@@ -343,7 +343,7 @@ const char g_aaKeyStrings[512][16] =
 	"mouse8",
 	"mousewheelup",
 	"mousewheeldown",
-	"&333",
+	"mouse9",
 	"&334",
 	"&335",
 	"&336",
diff --git a/src/engine/keys.h b/src/engine/keys.h
index 00e2c051f..9a138b973 100644
--- a/src/engine/keys.h
+++ b/src/engine/keys.h
@@ -248,6 +248,7 @@ enum
 	KEY_MOUSE_8 = 330,
 	KEY_MOUSE_WHEEL_UP = 331,
 	KEY_MOUSE_WHEEL_DOWN = 332,
+	KEY_MOUSE_9 = 333,
 	KEY_LAST,
 };