diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 9caa9c6665..0bb16f39ee 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -1298,6 +1298,7 @@ set (PCH_SOURCES
 	utility/nodebuilder/nodebuild_utility.cpp
 	utility/sc_man.cpp
 	utility/stats.cpp
+	utility/atterm.cpp
 	utility/cmdlib.cpp
 	utility/colormatcher.cpp
 	utility/configfile.cpp
diff --git a/src/d_main.cpp b/src/d_main.cpp
index f9db5fe0ed..12504081ca 100644
--- a/src/d_main.cpp
+++ b/src/d_main.cpp
@@ -102,6 +102,7 @@
 #include "i_system.h"
 #include "g_cvars.h"
 #include "r_data/r_vanillatrans.h"
+#include "atterm.h"
 
 EXTERN_CVAR(Bool, hud_althud)
 EXTERN_CVAR(Int, vr_mode)
diff --git a/src/dobjtype.cpp b/src/dobjtype.cpp
index c0c8e24323..d7ea265bc9 100644
--- a/src/dobjtype.cpp
+++ b/src/dobjtype.cpp
@@ -50,6 +50,7 @@
 #include "types.h"
 #include "scriptutil.h"
 #include "i_system.h"
+#include "atterm.h"
 
 // MACROS ------------------------------------------------------------------
 
diff --git a/src/doomtype.h b/src/doomtype.h
index 47a636552f..b361bf77c4 100644
--- a/src/doomtype.h
+++ b/src/doomtype.h
@@ -302,6 +302,11 @@ inline float DEG2RAD(float deg)
 	return deg * float(M_PI / 180.0);
 }
 
+inline double DEG2RAD(double deg)
+{
+	return deg * (M_PI / 180.0);
+}
+
 inline float RAD2DEG(float deg)
 {
 	return deg * float(180. / M_PI);
diff --git a/src/g_statusbar/sbarinfo.cpp b/src/g_statusbar/sbarinfo.cpp
index a2d1701fd8..f8929c9989 100644
--- a/src/g_statusbar/sbarinfo.cpp
+++ b/src/g_statusbar/sbarinfo.cpp
@@ -49,6 +49,7 @@
 #include "vm.h"
 #include "i_system.h"
 #include "utf8.h"
+#include "atterm.h"
 
 #define ARTIFLASH_OFFSET (statusBar->invBarOffset+6)
 enum
diff --git a/src/gamedata/g_mapinfo.cpp b/src/gamedata/g_mapinfo.cpp
index 9a0d04c9ac..42e06e2ba9 100644
--- a/src/gamedata/g_mapinfo.cpp
+++ b/src/gamedata/g_mapinfo.cpp
@@ -50,6 +50,7 @@
 #include "g_levellocals.h"
 #include "events.h"
 #include "i_system.h"
+#include "atterm.h"
 
 static TArray<cluster_info_t> wadclusterinfos;
 TArray<level_info_t> wadlevelinfos;
diff --git a/src/i_net.cpp b/src/i_net.cpp
index 4cbf1df23e..d2b17efb17 100644
--- a/src/i_net.cpp
+++ b/src/i_net.cpp
@@ -62,6 +62,7 @@
 #include "st_start.h"
 #include "m_misc.h"
 #include "doomerrors.h"
+#include "atterm.h"
 
 #include "i_net.h"
 
diff --git a/src/m_misc.cpp b/src/m_misc.cpp
index 42938fb809..cb980bf730 100644
--- a/src/m_misc.cpp
+++ b/src/m_misc.cpp
@@ -66,6 +66,7 @@
 
 #include "gameconfigfile.h"
 #include "gstrings.h"
+#include "atterm.h"
 
 FGameConfigFile *GameConfig;
 
diff --git a/src/menu/menudef.cpp b/src/menu/menudef.cpp
index 5eca78b010..a3bc152592 100644
--- a/src/menu/menudef.cpp
+++ b/src/menu/menudef.cpp
@@ -50,6 +50,7 @@
 #include "gstrings.h"
 #include "teaminfo.h"
 #include "r_data/sprites.h"
+#include "atterm.h"
 
 
 void ClearSaveGames();
diff --git a/src/p_setup.cpp b/src/p_setup.cpp
index 2842587b40..7d92b794c6 100644
--- a/src/p_setup.cpp
+++ b/src/p_setup.cpp
@@ -75,6 +75,7 @@
 #include "i_system.h"
 #include "v_video.h"
 #include "fragglescript/t_script.h"
+#include "atterm.h"
 
 extern AActor *SpawnMapThing (int index, FMapThing *mthing, int position);
 
diff --git a/src/posix/cocoa/i_joystick.cpp b/src/posix/cocoa/i_joystick.cpp
index a34c8b03d2..189845c4aa 100644
--- a/src/posix/cocoa/i_joystick.cpp
+++ b/src/posix/cocoa/i_joystick.cpp
@@ -42,6 +42,7 @@
 #include "m_joy.h"
 #include "templates.h"
 #include "v_text.h"
+#include "atterm.h"
 
 
 EXTERN_CVAR(Bool, joy_axespolling)
diff --git a/src/posix/cocoa/i_main.mm b/src/posix/cocoa/i_main.mm
index 7f823b628c..859fe675de 100644
--- a/src/posix/cocoa/i_main.mm
+++ b/src/posix/cocoa/i_main.mm
@@ -33,6 +33,7 @@
 
 #include "i_common.h"
 #include "s_sound.h"
+#include "atterm.h"
 
 #include <sys/sysctl.h>
 
@@ -64,57 +65,6 @@ EXTERN_CVAR(Bool, vid_vsync    )
 namespace
 {
 
-// The maximum number of functions that can be registered with atterm.
-const size_t MAX_TERMS = 64;
-
-void      (*TermFuncs[MAX_TERMS])();
-const char *TermNames[MAX_TERMS];
-size_t      NumTerms;
-
-} // unnamed namespace
-
-// Expose this for i_main_except.cpp
-void call_terms()
-{
-	while (NumTerms > 0)
-	{
-		TermFuncs[--NumTerms]();
-	}
-}
-
-
-void addterm(void (*func)(), const char *name)
-{
-	// Make sure this function wasn't already registered.
-
-	for (size_t i = 0; i < NumTerms; ++i)
-	{
-		if (TermFuncs[i] == func)
-		{
-			return;
-		}
-	}
-
-	if (NumTerms == MAX_TERMS)
-	{
-		func();
-		I_FatalError("Too many exit functions registered.");
-	}
-
-	TermNames[NumTerms] = name;
-	TermFuncs[NumTerms] = func;
-
-	++NumTerms;
-}
-
-void popterm()
-{
-	if (NumTerms)
-	{
-		--NumTerms;
-	}
-}
-
 
 void Mac_I_FatalError(const char* const message)
 {
diff --git a/src/posix/cocoa/i_main_except.cpp b/src/posix/cocoa/i_main_except.cpp
index afb0ba7e41..e67914a0e3 100644
--- a/src/posix/cocoa/i_main_except.cpp
+++ b/src/posix/cocoa/i_main_except.cpp
@@ -36,9 +36,9 @@
 
 #include "doomerrors.h"
 #include "vm.h"
+#include "atterm.h"
 
 // Import some functions from i_main.mm
-void call_terms();
 void Mac_I_FatalError(const char* const message);
 void OriginalMainTry(int argc, char** argv);
 
diff --git a/src/posix/cocoa/i_system.mm b/src/posix/cocoa/i_system.mm
index 04a6455409..ab17268e4d 100644
--- a/src/posix/cocoa/i_system.mm
+++ b/src/posix/cocoa/i_system.mm
@@ -48,6 +48,7 @@
 #include "v_text.h"
 #include "x86.h"
 #include "cmdlib.h"
+#include "atterm.h"
 
 
 EXTERN_CVAR(String, language)
diff --git a/src/posix/cocoa/i_video.mm b/src/posix/cocoa/i_video.mm
index 36738055b2..8d6b203f20 100644
--- a/src/posix/cocoa/i_video.mm
+++ b/src/posix/cocoa/i_video.mm
@@ -54,6 +54,7 @@
 #include "v_text.h"
 #include "version.h"
 #include "doomerrors.h"
+#include "atterm.h"
 
 #include "gl/system/gl_framebuffer.h"
 #include "vulkan/system/vk_framebuffer.h"
diff --git a/src/posix/i_system.h b/src/posix/i_system.h
index e6cd95cf88..0ef217aa1a 100644
--- a/src/posix/i_system.h
+++ b/src/posix/i_system.h
@@ -89,10 +89,6 @@ void I_Quit (void);
 
 void I_Tactile (int on, int off, int total);
 
-void addterm (void (*func)(void), const char *name);
-#define atterm(t) addterm (t, #t)
-void popterm ();
-
 void I_DebugPrint (const char *cp);
 
 // Print a console string
diff --git a/src/posix/sdl/hardware.cpp b/src/posix/sdl/hardware.cpp
index e631fa3132..eb71e6e97b 100644
--- a/src/posix/sdl/hardware.cpp
+++ b/src/posix/sdl/hardware.cpp
@@ -43,6 +43,7 @@
 #include "m_argv.h"
 #include "doomerrors.h"
 #include "swrenderer/r_swrenderer.h"
+#include "atterm.h"
 
 IVideo *Video;
 
diff --git a/src/posix/sdl/i_main.cpp b/src/posix/sdl/i_main.cpp
index caddfcf870..5720942171 100644
--- a/src/posix/sdl/i_main.cpp
+++ b/src/posix/sdl/i_main.cpp
@@ -56,6 +56,7 @@
 #include "doomerrors.h"
 #include "i_system.h"
 #include "g_game.h"
+#include "atterm.h"
 
 // MACROS ------------------------------------------------------------------
 
@@ -89,47 +90,9 @@ FArgs *Args;
 
 // PRIVATE DATA DEFINITIONS ------------------------------------------------
 
-static void (*TermFuncs[MAX_TERMS]) ();
-static const char *TermNames[MAX_TERMS];
-static int NumTerms;
 
 // CODE --------------------------------------------------------------------
 
-void addterm (void (*func) (), const char *name)
-{
-	// Make sure this function wasn't already registered.
-	for (int i = 0; i < NumTerms; ++i)
-	{
-		if (TermFuncs[i] == func)
-		{
-			return;
-		}
-	}
-    if (NumTerms == MAX_TERMS)
-	{
-		func ();
-		I_FatalError (
-			"Too many exit functions registered.\n"
-			"Increase MAX_TERMS in i_main.cpp");
-	}
-	TermNames[NumTerms] = name;
-    TermFuncs[NumTerms++] = func;
-}
-
-void popterm ()
-{
-	if (NumTerms)
-		NumTerms--;
-}
-
-void call_terms ()
-{
-    while (NumTerms > 0)
-	{
-//		printf ("term %d - %s\n", NumTerms, TermNames[NumTerms-1]);
-		TermFuncs[--NumTerms] ();
-	}
-}
 
 static void NewFailure ()
 {
diff --git a/src/posix/sdl/i_system.cpp b/src/posix/sdl/i_system.cpp
index 2b8fd91556..b59725e7bf 100644
--- a/src/posix/sdl/i_system.cpp
+++ b/src/posix/sdl/i_system.cpp
@@ -51,6 +51,7 @@
 #include "d_net.h"
 #include "g_game.h"
 #include "c_dispatch.h"
+#include "atterm.h"
 
 #include "gameconfigfile.h"
 
diff --git a/src/posix/sdl/st_start.cpp b/src/posix/sdl/st_start.cpp
index 38959f542d..fa8ebe209f 100644
--- a/src/posix/sdl/st_start.cpp
+++ b/src/posix/sdl/st_start.cpp
@@ -42,6 +42,7 @@
 #include "doomdef.h"
 #include "i_system.h"
 #include "c_cvars.h"
+#include "atterm.h"
 
 // MACROS ------------------------------------------------------------------
 
diff --git a/src/r_utility.cpp b/src/r_utility.cpp
index c258d0df84..3bab7e0855 100644
--- a/src/r_utility.cpp
+++ b/src/r_utility.cpp
@@ -64,6 +64,7 @@
 #include "actorinlines.h"
 #include "g_game.h"
 #include "i_system.h"
+#include "atterm.h"
 
 // EXTERNAL DATA DECLARATIONS ----------------------------------------------
 
diff --git a/src/rendering/swrenderer/r_swcolormaps.cpp b/src/rendering/swrenderer/r_swcolormaps.cpp
index 712107be8b..23dbf1281a 100644
--- a/src/rendering/swrenderer/r_swcolormaps.cpp
+++ b/src/rendering/swrenderer/r_swcolormaps.cpp
@@ -55,6 +55,7 @@
 #include "templates.h"
 #include "r_utility.h"
 #include "r_renderer.h"
+#include "atterm.h"
 #include <atomic>
 
 FDynamicColormap NormalLight;
diff --git a/src/s_advsound.cpp b/src/s_advsound.cpp
index 054edd6fb4..b869473a2b 100644
--- a/src/s_advsound.cpp
+++ b/src/s_advsound.cpp
@@ -48,6 +48,7 @@
 #include "r_data/sprites.h"
 #include "vm.h"
 #include "i_system.h"
+#include "atterm.h"
 
 // MACROS ------------------------------------------------------------------
 
diff --git a/src/s_environment.cpp b/src/s_environment.cpp
index 8bd9661c7d..cfc9e87b89 100644
--- a/src/s_environment.cpp
+++ b/src/s_environment.cpp
@@ -46,6 +46,7 @@
 #include "vm.h"
 #include "dobject.h"
 #include "menu/menu.h"
+#include "atterm.h"
 
 
 
diff --git a/src/s_sound.cpp b/src/s_sound.cpp
index 2198431721..762b1db07c 100644
--- a/src/s_sound.cpp
+++ b/src/s_sound.cpp
@@ -83,6 +83,7 @@
 #include "g_levellocals.h"
 #include "vm.h"
 #include "g_game.h"
+#include "atterm.h"
 
 // MACROS ------------------------------------------------------------------
 
diff --git a/src/utility/atterm.cpp b/src/utility/atterm.cpp
new file mode 100644
index 0000000000..51270ec038
--- /dev/null
+++ b/src/utility/atterm.cpp
@@ -0,0 +1,97 @@
+/*
+** attern.cpp
+** Termination handling
+**
+**---------------------------------------------------------------------------
+** Copyright 1998-2007 Randy Heit
+** Copyright 2019 Christoph Oelckers
+** All rights reserved.
+**
+** Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions
+** are met:
+**
+** 1. Redistributions of source code must retain the above copyright
+**    notice, this list of conditions and the following disclaimer.
+** 2. Redistributions in binary form must reproduce the above copyright
+**    notice, this list of conditions and the following disclaimer in the
+**    documentation and/or other materials provided with the distribution.
+** 3. The name of the author may not be used to endorse or promote products
+**    derived from this software without specific prior written permission.
+**
+** THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+** IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+** OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+** IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+** NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+** THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+**---------------------------------------------------------------------------
+**
+*/
+
+
+#include <algorithm>
+#include "tarray.h"
+#include "atterm.h"
+
+static TArray<std::pair<void (*)(void), const char *>> TermFuncs;
+
+
+//==========================================================================
+//
+// atterm
+//
+// Our own atexit because atexit can be problematic under Linux, though I
+// forget the circumstances that cause trouble.
+//
+//==========================================================================
+
+void addterm(void (*func)(), const char *name)
+{
+	// Make sure this function wasn't already registered.
+
+	for (auto &term : TermFuncs)
+	{
+		if (term.first == func)
+		{
+			return;
+		}
+	}
+	TermFuncs.Push(std::make_pair(func, name));
+}
+
+//==========================================================================
+//
+// call_terms
+//
+//==========================================================================
+
+void call_terms()
+{
+	for(int i = TermFuncs.Size()-1; i >= 0; i--)
+	{
+		TermFuncs[i].first();
+	}
+	TermFuncs.Clear();
+}
+
+//==========================================================================
+//
+// popterm
+//
+// Removes the most recently register atterm function.
+//
+//==========================================================================
+
+void popterm()
+{
+	if (TermFuncs.Size() > 0)
+	{
+		TermFuncs.Pop();
+	}
+}
+
diff --git a/src/utility/atterm.h b/src/utility/atterm.h
new file mode 100644
index 0000000000..6c1a463c79
--- /dev/null
+++ b/src/utility/atterm.h
@@ -0,0 +1,6 @@
+#pragma once
+
+void addterm (void (*func)(void), const char *name);
+#define atterm(t) addterm (t, #t)
+void popterm ();
+void call_terms();
diff --git a/src/v_video.cpp b/src/v_video.cpp
index 9df3714779..645fc97192 100644
--- a/src/v_video.cpp
+++ b/src/v_video.cpp
@@ -69,6 +69,7 @@
 #include "version.h"
 #include "g_levellocals.h"
 #include "am_map.h"
+#include "atterm.h"
 
 EXTERN_CVAR(Int, menu_resolution_custom_width)
 EXTERN_CVAR(Int, menu_resolution_custom_height)
diff --git a/src/win32/hardware.cpp b/src/win32/hardware.cpp
index 0a5457eef4..2674d553ae 100644
--- a/src/win32/hardware.cpp
+++ b/src/win32/hardware.cpp
@@ -50,6 +50,7 @@
 #include "doomerrors.h"
 #include "i_system.h"
 #include "swrenderer/r_swrenderer.h"
+#include "atterm.h"
 
 EXTERN_CVAR(Int, vid_enablevulkan)
 
diff --git a/src/win32/i_cd.cpp b/src/win32/i_cd.cpp
index a127a13780..cd00fbcfc9 100644
--- a/src/win32/i_cd.cpp
+++ b/src/win32/i_cd.cpp
@@ -46,6 +46,7 @@
 
 #include "i_cd.h"
 #include "helperthread.h"
+#include "atterm.h"
 
 extern HWND Window;
 extern HINSTANCE g_hInst;
diff --git a/src/win32/i_input.cpp b/src/win32/i_input.cpp
index 7753566e9d..a6b2e39395 100644
--- a/src/win32/i_input.cpp
+++ b/src/win32/i_input.cpp
@@ -92,6 +92,7 @@
 #include "doomerrors.h"
 #include "i_system.h"
 #include "g_levellocals.h"
+#include "atterm.h"
 
 // Prototypes and declarations.
 #include "rawinput.h"
diff --git a/src/win32/i_main.cpp b/src/win32/i_main.cpp
index 4f42f7593b..0bfcc2e0c6 100644
--- a/src/win32/i_main.cpp
+++ b/src/win32/i_main.cpp
@@ -74,6 +74,7 @@
 #include "vm.h"
 #include "i_system.h"
 #include "gstrings.h"
+#include "atterm.h"
 
 #include "stats.h"
 #include "st_start.h"
@@ -153,65 +154,9 @@ DYN_WIN32_SYM(SHGetKnownFolderPath);
 
 static const WCHAR WinClassName[] = WGAMENAME "MainWindow";
 static HMODULE hwtsapi32;		// handle to wtsapi32.dll
-static void (*TermFuncs[MAX_TERMS])(void);
-static int NumTerms;
 
 // CODE --------------------------------------------------------------------
 
-//==========================================================================
-//
-// atterm
-//
-// Our own atexit because atexit can be problematic under Linux, though I
-// forget the circumstances that cause trouble.
-//
-//==========================================================================
-
-void atterm (void (*func)(void))
-{
-	// Make sure this function wasn't already registered.
-	for (int i = 0; i < NumTerms; ++i)
-	{
-		if (TermFuncs[i] == func)
-		{
-			return;
-		}
-	}
-	if (NumTerms == MAX_TERMS)
-	{
-		func ();
-		I_FatalError ("Too many exit functions registered.\nIncrease MAX_TERMS in i_main.cpp");
-	}
-	TermFuncs[NumTerms++] = func;
-}
-
-//==========================================================================
-//
-// popterm
-//
-// Removes the most recently register atterm function.
-//
-//==========================================================================
-
-void popterm ()
-{
-	if (NumTerms)
-		NumTerms--;
-}
-
-//==========================================================================
-//
-// call_terms
-//
-//==========================================================================
-
-static void call_terms (void)
-{
-	while (NumTerms > 0)
-	{
-		TermFuncs[--NumTerms]();
-	}
-}
 
 #ifdef _MSC_VER
 static int NewFailure (size_t size)
diff --git a/src/win32/i_system.cpp b/src/win32/i_system.cpp
index cc7727cd05..fc3ce169b2 100644
--- a/src/win32/i_system.cpp
+++ b/src/win32/i_system.cpp
@@ -84,6 +84,7 @@
 #include "doomstat.h"
 #include "i_system.h"
 #include "textures/bitmap.h"
+#include "atterm.h"
 
 #include "optwin32.h"
 
diff --git a/src/win32/i_system.h b/src/win32/i_system.h
index 5a5b663f98..4a28b7f91a 100644
--- a/src/win32/i_system.h
+++ b/src/win32/i_system.h
@@ -80,9 +80,6 @@ void I_Quit (void);
 
 void I_Tactile (int on, int off, int total);
 
-void atterm (void (*func)(void));
-void popterm ();
-
 // Set the mouse cursor. The texture must be 32x32.
 class FTexture;
 bool I_SetCursor(FTexture *cursor);