diff --git a/Makefile b/Makefile
index 3e48ba9..58872d8 100644
--- a/Makefile
+++ b/Makefile
@@ -253,16 +253,20 @@ POSIX_BOOT =  $(COMMON_PHASE1) \
 $(GEN)/posix_boot.h: tools/source_to_string.js $(POSIX_BOOT) | $(GEN)
 	$< boot $(VERSION) $(REVISION) $(POSIX_BOOT) >$@
 
+WINDOWS_BOOT_EXTRA = windows/windows_user.fs \
+                     windows/windows_gdi.fs \
+                     windows/windows_messages.fs \
+                     windows/graphics.fs
+$(GEN)/windows_boot_extra.h: tools/source_to_string.js $(WINDOWS_BOOT_EXTRA) | $(GEN)
+	$< -win boot_extra $(VERSION) $(REVISION) $(WINDOWS_BOOT_EXTRA) >$@
+
 WINDOWS_BOOT = $(COMMON_PHASE1) \
                windows/windows_core.fs \
                windows/windows_files.fs \
                windows/windows_console.fs \
-               windows/windows_user.fs \
-               windows/windows_gdi.fs \
-               windows/windows_messages.fs \
                windows/allocation.fs \
                $(COMMON_PHASE2) $(COMMON_FILETOOLS) $(COMMON_DESKTOP) \
-               windows/graphics.fs \
+               windows/load_extra.fs \
                posix/autoboot.fs \
                common/fini.fs
 $(GEN)/windows_boot.h: tools/source_to_string.js $(WINDOWS_BOOT) | $(GEN)
@@ -404,6 +408,7 @@ $(WINDOWS)/uEf32.obj: \
     common/bits.h \
     common/core.h \
     windows/interp.h \
+    $(GEN)/windows_boot_extra.h \
     $(GEN)/windows_boot.h | $(WINDOWS)
 	$(CL32) /c /Fo$@ $(WIN_CFLAGS) $<
 
@@ -423,6 +428,7 @@ $(WINDOWS)/uEf64.obj: \
     common/bits.h \
     common/core.h \
     windows/interp.h \
+    $(GEN)/windows_boot_extra.h \
     $(GEN)/windows_boot.h | $(WINDOWS)
 	$(CL64) /c /Fo$@ $(WIN_CFLAGS) $<
 
diff --git a/common/forth_namespace_tests.fs b/common/forth_namespace_tests.fs
index e43823a..e3515a9 100644
--- a/common/forth_namespace_tests.fs
+++ b/common/forth_namespace_tests.fs
@@ -467,6 +467,7 @@ e: check-args
 ;e
 
 e: check-imports
+  out: file-exists? 
   out: needs 
   out: required 
   out: included? 
diff --git a/common/including.fs b/common/including.fs
index 609999b..dc0abf6 100644
--- a/common/including.fs
+++ b/common/including.fs
@@ -78,11 +78,12 @@ forth definitions internals
 : included ( a n -- )
    sourcefilename >r >r
    >r >r sourcedirname r> r> path-join 2dup sourcefilename!
-   ['] raw-included catch
-   dup if ." Error including: " sourcefilename type cr then
+   ['] raw-included catch if
+      ." Error including: " sourcefilename type cr
+      -38 throw
+   then
    sourcefilename& include+
-   r> r> sourcefilename!
-   throw ;
+   r> r> sourcefilename! ;
 
 : include ( "name" -- ) bl parse included ;
 
@@ -98,4 +99,6 @@ forth definitions internals
 : required ( a n -- ) 2dup included? if 2drop else included then ;
 : needs ( "name" -- ) bl parse required ;
 
+: file-exists? ( "name" -- f ) r/o open-file if drop 0 else close-file throw -1 then ;
+
 forth
diff --git a/esp32/autoboot.fs b/esp32/autoboot.fs
index 179c56c..a4054a6 100644
--- a/esp32/autoboot.fs
+++ b/esp32/autoboot.fs
@@ -25,8 +25,10 @@ internals definitions
 ( Check for autoexec.fs and run if present.
   Failing that, try to revive save image. )
 : autoexec
-   300 for key? if rdrop exit then 10 ms next
-   s" /spiffs/autoexec.fs" ['] included catch 2drop drop
+   ( Allow skip start files if key hit within 100 ms )
+   10 for key? if rdrop exit then 10 ms next
+   s" /spiffs/autoexec.fs" 2dup file-exists?
+     if included else 2drop then
    ['] revive catch drop ;
 ' autoexec ( leave on the stack for fini.fs )
 
diff --git a/posix/posix.fs b/posix/posix.fs
index fd01cfd..d206dac 100644
--- a/posix/posix.fs
+++ b/posix/posix.fs
@@ -26,11 +26,11 @@ internals
 ' call10 , ' call11 , ' call12 , ' call13 , ' call14 , ' call15 ,
 posix
 : sofunc ( z n a "name" -- )
-   swap >r swap dlsym dup 0= throw create , r> cells calls + @ ,
+   swap >r swap dlsym dup 0= -38 and throw create , r> cells calls + @ ,
    does> dup @ swap cell+ @ execute ;
 : sysfunc ( z n "name" -- ) 0 sofunc ;
 : shared-library ( z "name" -- )
-   RTLD_NOW dlopen dup 0= throw create , does> @ sofunc ;
+   RTLD_NOW dlopen dup 0= -38 and throw create , does> @ sofunc ;
 : sign-extend ( n -- n ) >r rp@ sl@ rdrop ;
 
 ( Major Syscalls )
diff --git a/windows/load_extra.fs b/windows/load_extra.fs
new file mode 100644
index 0000000..485f17a
--- /dev/null
+++ b/windows/load_extra.fs
@@ -0,0 +1,16 @@
+\ Copyright 2023 Bradley D. Nelson
+\
+\ 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.
+
+( Load extra things that didn't fit in main boot string. )
+windows boot_extra forth evaluate
diff --git a/windows/main.c b/windows/main.c
index 8935133..5896f17 100644
--- a/windows/main.c
+++ b/windows/main.c
@@ -38,6 +38,7 @@
 
 static LRESULT WindowProcShim(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam);
 static void SetupCtrlBreakHandler(void);
+static cell_t GetBootExtra(cell_t *start);
 
 #define PLATFORM_OPCODE_LIST \
   YV(windows, GetProcAddress, \
@@ -45,6 +46,7 @@ static void SetupCtrlBreakHandler(void);
   YV(windows, LoadLibraryA, tos = (cell_t) LoadLibraryA((LPCSTR) tos)) \
   YV(windows, WindowProcShim, DUP; tos = (cell_t) &WindowProcShim) \
   YV(windows, SetupCtrlBreakHandler, SetupCtrlBreakHandler()) \
+  YV(windows, boot_extra, DUP; DUP; tos = GetBootExtra(sp)) \
   CALLING_OPCODE_LIST \
   FLOATING_POINT_LIST
 
@@ -56,6 +58,7 @@ static void SetupCtrlBreakHandler(void);
 #include "windows/interp.h"
 
 #include "gen/windows_boot.h"
+#include "gen/windows_boot_extra.h"
 
 static DWORD forth_main_thread_id;
 static uintptr_t forth_main_thread_resume_sp;
@@ -108,6 +111,11 @@ static void SetupCtrlBreakHandler(void) {
 #endif
 }
 
+static cell_t GetBootExtra(cell_t *start) {
+  *start = (cell_t) boot_extra;
+  return (cell_t) sizeof(boot_extra) - 1;
+}
+
 static LRESULT WindowProcShim(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam) {
   if (msg == WM_NCCREATE) {
     SetWindowLongPtr(