diff --git a/class.c b/class.c
index f83a16a08e8..54796905891 100644
--- a/class.c
+++ b/class.c
@@ -847,6 +847,8 @@ rb_define_class(const char *name, VALUE super)
 		     name, rb_obj_class(klass));
 	}
 	if (rb_class_real(RCLASS_SUPER(klass)) != super) {
+        // edited for mkxp-z compatibility
+        goto override_class;
 	    rb_raise(rb_eTypeError, "superclass mismatch for class %s", name);
 	}
 
@@ -854,6 +856,7 @@ rb_define_class(const char *name, VALUE super)
         rb_vm_add_root_module(klass);
 	return klass;
     }
+override_class:
     if (!super) {
 	rb_raise(rb_eArgError, "no super class for `%s'", name);
     }
diff --git a/configure.ac b/configure.ac
index 5a6b074f8a1..67b3a232641 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1129,7 +1129,7 @@ main()
 		AC_CHECK_FUNCS(cygwin_conv_path)
 		AC_LIBOBJ([langinfo])
 		],
-[mingw*], [	LIBS="-lshell32 -lws2_32 -liphlpapi -limagehlp -lshlwapi -lbcrypt $LIBS"
+[mingw*], [	LIBS="-lshell32 -lws2_32 -liphlpapi -limagehlp -lshlwapi -lbcrypt -Wl,-Bstatic -lgcc -lpthread -lz -lffi -Wl,-Bdynamic $LIBS"
 		ac_cv_header_pwd_h=no
 		ac_cv_header_utime_h=no
 		ac_cv_header_sys_ioctl_h=no
diff --git a/include/ruby/win32.h b/include/ruby/win32.h
index c8ae599f2f8..d46dc32ac51 100644
--- a/include/ruby/win32.h
+++ b/include/ruby/win32.h
@@ -157,7 +157,7 @@ typedef int clockid_t;
 #define getpid()		rb_w32_getpid()
 #define getppid()		rb_w32_getppid()
 #define sleep(x)		rb_w32_Sleep((x)*1000)
-#define Sleep(msec)		(void)rb_w32_Sleep(msec)
+#define RB_Sleep(msec)		(void)rb_w32_Sleep(msec)
 
 #undef execv
 #define execv(path,argv)	rb_w32_uaspawn(P_OVERLAY,path,argv)
diff --git a/sprintf.c b/sprintf.c
index f4aa7f6d1d0..2d5052f1ddd 100644
--- a/sprintf.c
+++ b/sprintf.c
@@ -931,11 +931,13 @@ rb_str_format(int argc, const VALUE *argv, VALUE fmt)
     rb_str_tmp_frozen_release(orig, fmt);
     /* XXX - We cannot validate the number of arguments if (digit)$ style used.
      */
+#if 0
     if (posarg >= 0 && nextarg < argc) {
 	const char *mesg = "too many arguments for format string";
 	if (RTEST(ruby_debug)) rb_raise(rb_eArgError, "%s", mesg);
 	if (RTEST(ruby_verbose)) rb_warn("%s", mesg);
     }
+#endif
     rb_str_resize(result, blen);
 
     return result;
diff --git a/thread_win32.c b/thread_win32.c
index 026ccc4c600..778048c2b6b 100644
--- a/thread_win32.c
+++ b/thread_win32.c
@@ -16,7 +16,7 @@
 #define TIME_QUANTUM_USEC (10 * 1000)
 #define RB_CONDATTR_CLOCK_MONOTONIC 1 /* no effect */
 
-#undef Sleep
+//#undef Sleep
 
 #define native_thread_yield() Sleep(0)
 #define unregister_ubf_list(th)
diff --git a/vm_eval.c b/vm_eval.c
index 0abb4644f9d..59e4b0bef2b 100644
--- a/vm_eval.c
+++ b/vm_eval.c
@@ -828,7 +828,7 @@ rb_method_call_status(rb_execution_context_t *ec, const rb_callable_method_entry
     rb_method_visibility_t visi = METHOD_ENTRY_VISI(me);
 
     /* receiver specified form for private method */
-    if (UNLIKELY(visi != METHOD_VISI_PUBLIC)) {
+    if (0) { //UNLIKELY(visi != METHOD_VISI_PUBLIC)) {
         if (me->def->original_id == idMethodMissing) {
             return MISSING_NONE;
         }
diff --git a/vm_insnhelper.c b/vm_insnhelper.c
index e01d39de77a..fc88e41b210 100644
--- a/vm_insnhelper.c
+++ b/vm_insnhelper.c
@@ -3722,9 +3722,11 @@ vm_call_method(rb_execution_context_t *ec, rb_control_frame_t *cfp, struct rb_ca
     if (vm_cc_cme(cc) != NULL) {
 	switch (METHOD_ENTRY_VISI(vm_cc_cme(cc))) {
 	  case METHOD_VISI_PUBLIC: /* likely */
+call_anyway:
             return vm_call_method_each_type(ec, cfp, calling);
 
 	  case METHOD_VISI_PRIVATE:
+        goto call_anyway;
 	    if (!(vm_ci_flag(ci) & VM_CALL_FCALL)) {
 		enum method_missing_reason stat = MISSING_PRIVATE;
 		if (vm_ci_flag(ci) & VM_CALL_VCALL) stat |= MISSING_VCALL;
@@ -3736,6 +3738,7 @@ vm_call_method(rb_execution_context_t *ec, rb_control_frame_t *cfp, struct rb_ca
             return vm_call_method_each_type(ec, cfp, calling);
 
 	  case METHOD_VISI_PROTECTED:
+        goto call_anyway;
 	    if (!(vm_ci_flag(ci) & VM_CALL_OPT_SEND)) {
 		if (!rb_obj_is_kind_of(cfp->self, vm_cc_cme(cc)->defined_class)) {
                     vm_cc_method_missing_reason_set(cc, MISSING_PROTECTED);
@@ -4476,7 +4479,7 @@ vm_check_if_class(ID id, rb_num_t flags, VALUE super, VALUE klass)
     else if (VM_DEFINECLASS_HAS_SUPERCLASS_P(flags)) {
 	VALUE tmp = rb_class_real(RCLASS_SUPER(klass));
 
-	if (tmp != super) {
+	if (0) { //tmp != super) {
 	    rb_raise(rb_eTypeError,
 		     "superclass mismatch for class %"PRIsVALUE"",
 		     rb_id2str(id));
diff --git a/win32/win32.c b/win32/win32.c
index c938e197a7d..12711b66b21 100644
--- a/win32/win32.c
+++ b/win32/win32.c
@@ -1375,7 +1375,7 @@ rb_w32_start_process(const char *abspath, char *const *argv, int out_fd)
         return NULL;
     }
 
-    if (!CreateChild(&child, wcmd, wprog, NULL, outHandle, outHandle, 0)) {
+    if (!CreateChild(&child, wcmd, wprog, NULL, outHandle, outHandle, CREATE_NO_WINDOW)) {
         return NULL;
     }
 
@@ -3187,7 +3187,7 @@ compare(const struct timeval *t1, const struct timeval *t2)
     return 0;
 }
 
-#undef Sleep
+//#undef Sleep
 
 int rb_w32_check_interrupt(void *);	/* @internal */