diff --git a/Makefile.in b/Makefile.in
index bfb3ae32d3..f17579f6e4 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -78,6 +78,7 @@ MISSING = @LIBOBJS@ @ALLOCA@
 LDSHARED = @LIBRUBY_LDSHARED@
 DLDFLAGS = @LIBRUBY_DLDFLAGS@ $(XLDFLAGS) $(ARCH_FLAG)
 SOLIBS = @SOLIBS@
+ENABLE_DEBUG_ENV = @ENABLE_DEBUG_ENV@
 MAINLIBS = @MAINLIBS@
 ARCHMINIOBJS = @MINIOBJS@
 DLNOBJ = @DLNOBJ@
@@ -195,6 +196,8 @@ MINIPRELUDE_C = miniprelude.c
 PRELUDE_C     = prelude.c
 RBCONFIG      = .rbconfig.time
 
+MAINSRC = $(MAINOBJ:@OBJEXT@=c)
+
 SRC_FILE      = $<
 OS_SRC_FILE   = $<
 DEST_FILE     = $@
diff --git a/common.mk b/common.mk
index b2c1eb0633..9e554753c6 100644
--- a/common.mk
+++ b/common.mk
@@ -938,6 +938,12 @@ $(PRELUDE_C): $(COMPILE_PRELUDE) \
 	$(Q) $(BASERUBY) $(srcdir)/tool/generic_erb.rb -I$(srcdir) -c -o $@ \
 		$(srcdir)/template/prelude.c.tmpl golf_prelude.rb
 
+MAINCPPFLAGS = $(ENABLE_DEBUG_ENV:yes=-DRUBY_DEBUG_ENV=1)
+
+$(MAINOBJ): $(srcdir)/$(MAINSRC)
+	$(ECHO) compiling $(srcdir)/$(MAINSRC)
+	$(Q) $(CC) $(MAINCPPFLAGS) $(CFLAGS) $(XCFLAGS) $(CPPFLAGS) $(COUTFLAG)$@ -c $(CSRCFLAG)$(srcdir)/$(MAINSRC)
+
 {$(VPATH)}probes.dmyh: {$(srcdir)}probes.d $(srcdir)/tool/gen_dummy_probes.rb
 
 probes.dmyh:
diff --git a/configure.in b/configure.in
index a2ab09bb76..3933db8a7b 100644
--- a/configure.in
+++ b/configure.in
@@ -4209,7 +4209,7 @@ AS_CASE(["$THREAD_MODEL"],
 
 AC_ARG_ENABLE(debug-env,
        AS_HELP_STRING([--enable-debug-env], [enable RUBY_DEBUG environment variable]),
-       [AC_DEFINE(RUBY_DEBUG_ENV)])
+       [AC_SUBST(ENABLE_DEBUG_ENV, yes)])
 
 AS_CASE(["$FIRSTMAKEFILE"], [*GNUmakefile:*], [gnumake=yes], [
     AC_MSG_CHECKING([if ${MAKE-make} is GNU make])
diff --git a/main.c b/main.c
index 16da117732..764d947af3 100644
--- a/main.c
+++ b/main.c
@@ -15,6 +15,9 @@
 #ifdef HAVE_LOCALE_H
 #include <locale.h>
 #endif
+#if defined RUBY_DEBUG_ENV && !RUBY_DEBUG_ENV
+# undef RUBY_DEBUG_ENV
+#endif
 #ifdef RUBY_DEBUG_ENV
 #include <stdlib.h>
 #endif
diff --git a/win32/Makefile.sub b/win32/Makefile.sub
index e1a283e73f..2f59d83b0b 100644
--- a/win32/Makefile.sub
+++ b/win32/Makefile.sub
@@ -364,6 +364,7 @@ OS_DEST_FILE = $(@:/=\)
 !if !defined(WINMAINOBJ)
 WINMAINOBJ    = winmain.$(OBJEXT)
 !endif
+MAINSRC       = $(MAINOBJ:.obj=.c)
 ARCHMINIOBJS  = dmydln.$(OBJEXT) miniruby.res
 LIBOBJS       = $(MISSING) $(LIBOBJS)
 
@@ -772,9 +773,6 @@ $(CONFIG_H): $(MKFILES) $(srcdir)/win32/Makefile.sub $(win_srcdir)/Makefile.sub
 !endif
 #define CANONICALIZATION_FOR_MATHN 1
 #define DEFAULT_KCODE KCODE_NONE
-!if "$(ENABLE_DEBUG_ENV)" == "yes"
-#define RUBY_DEBUG_ENV 1
-!endif
 #define LOAD_RELATIVE 1
 #define DLEXT ".so"
 !if "$(EXTSTATIC)" == "static"