diff --git a/src/Make_cyg.mak b/src/Make_cyg.mak
index eaf7309..0a869dc 100644
--- a/src/Make_cyg.mak
+++ b/src/Make_cyg.mak
@@ -212,13 +212,34 @@
 MZSCHEME_VER = 209_000
 endif
 
+ifndef MZSCHEME_PRECISE_GC
+MZSCHEME_PRECISE_GC=no
+endif
+
+# for version 4.x we need to generate byte-code for Scheme base
+ifndef MZSCHEME_GENERATE_BASE
+MZSCHEME_GENERATE_BASE=no
+endif
+
 ifeq (yes, $(DYNAMIC_MZSCHEME))
 DEFINES += -DDYNAMIC_MZSCHEME -DDYNAMIC_MZSCH_DLL=\"libmzsch$(MZSCHEME_VER).dll\" -DDYNAMIC_MZGC_DLL=\"libmzgc$(MZSCHEME_VER).dll\"
 else
 ifndef MZSCHEME_DLLS
 MZSCHEME_DLLS = $(MZSCHEME)
 endif
-EXTRA_LIBS += -L$(MZSCHEME_DLLS) -lmzsch$(MZSCHEME_VER) -lmzgc$(MZSCHEME_VER)
+ifeq (yes,$(MZSCHEME_PRECISE_GC))
+MZSCHEME_LIB=-lmzsch$(MZSCHEME_VER)
+else
+MZSCHEME_LIB = -lmzsch$(MZSCHEME_VER) -lmzgc$(MZSCHEME_VER)
+endif
+EXTRA_LIBS += -L$(MZSCHEME_DLLS) -L$(MZSCHEME_DLLS)/lib $(MZSCHEME_LIB)
+endif
+ifeq (yes,$(MZSCHEME_GENERATE_BASE))
+DEFINES += -DINCLUDE_MZSCHEME_BASE
+MZ_EXTRA_DEP += mzscheme_base.c
+endif
+ifeq (yes,$(MZSCHEME_PRECISE_GC))
+DEFINES += -DMZ_PRECISE_GC
 endif
 endif
 
@@ -473,6 +494,9 @@
 ifdef PERL
 	-$(DEL) if_perl.c
 endif
+ifdef MZSCHEME
+	-$(DEL) mzscheme_base.c
+endif
 	-$(DEL) pathdef.c
 	$(MAKE) -C xxd -f Make_cyg.mak clean
 	$(MAKE) -C GvimExt -f Make_ming.mak clean
@@ -523,9 +547,15 @@
 $(OUTDIR)/netbeans.o:	netbeans.c $(INCL) $(NBDEBUG_DEP)
 	$(CC) -c $(CFLAGS) netbeans.c -o $(OUTDIR)/netbeans.o
 
+$(OUTDIR)/if_mzsch.o:	if_mzsch.c $(INCL) if_mzsch.h $(MZ_EXTRA_DEP)
+	$(CC) -c $(CFLAGS) if_mzsch.c -o $(OUTDIR)/if_mzsch.o
+
 $(OUTDIR)/vimrc.o:	vim.rc version.h gui_w32_rc.h
 	$(RC) $(RCFLAGS) vim.rc -o $(OUTDIR)/vimrc.o
 
+mzscheme_base.c:
+	$(MZSCHEME)/mzc --c-mods mzscheme_base.c ++lib scheme/base
+
 pathdef.c: $(INCL)
 ifneq (sh.exe, $(SHELL))
 	@echo creating pathdef.c
diff --git a/src/Make_ming.mak b/src/Make_ming.mak
index e0717b6..ae28a3d 100644
--- a/src/Make_ming.mak
+++ b/src/Make_ming.mak
@@ -135,7 +135,7 @@
 ifndef MZSCHEME_DLLS
 MZSCHEME_DLLS=$(MZSCHEME)
 endif
-MZSCHEME_LIBDIR=-L$(MZSCHEME_DLLS)
+MZSCHEME_LIBDIR=-L$(MZSCHEME_DLLS) -L$(MZSCHEME_DLLS)\lib
 endif
 
 endif
@@ -563,6 +563,9 @@
 ifdef PERL
 	-$(DEL) if_perl.c
 endif
+ifdef MZSCHEME
+	-$(DEL) mzscheme_base.c
+endif
 	$(MAKE) -C GvimExt -f Make_ming.mak clean
 	$(MAKE) -C xxd -f Make_cyg.mak clean
 
diff --git a/src/Make_mvc.mak b/src/Make_mvc.mak
index 72e722b..15a14ad 100644
--- a/src/Make_mvc.mak
+++ b/src/Make_mvc.mak
@@ -865,6 +865,7 @@
 	- if exist dimm_i.c del dimm_i.c
 	- if exist dimm.tlb del dimm.tlb
 	- if exist dosinst.exe del dosinst.exe
+	- if exist mzscheme_base.c del mzscheme_base.c
 	cd xxd
 	$(MAKE) /NOLOGO -f Make_mvc.mak clean
 	cd ..
diff --git a/src/version.c b/src/version.c
index 767152e..5a34c87 100644
--- a/src/version.c
+++ b/src/version.c
@@ -677,6 +677,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    248,
+/**/
     247,
 /**/
     246,