diff --git a/Makefile.in b/Makefile.in
index 9f01868e79..2451846eeb 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -542,29 +542,28 @@ mjit_config.h:
 	echo '#ifndef RUBY_MJIT_CONFIG_H'; \
 	echo '#define RUBY_MJIT_CONFIG_H 1'; \
 	\
-	set x $(CC) && shift && echo '#define MJIT_CC_COMMON "'$$1'"' \\; \
-	shift && for w do echo ' , "'$$w'"' \\; done; \
+	set x $(CC) && shift && echo '#define MJIT_CC_COMMON \\' && \
+	for w do echo '        "'$$w'", \\'; done; \
 	echo ' /* MJIT_CC_COMMON */'; \
 	\
-	\
-	set x -w $(ARCH_FLAG) && shift && echo '#define MJIT_CFLAGS "'$$1'"' \\; \
-	shift && for w do echo ' , "'$$w'"' \\; done; \
+	set x -w $(ARCH_FLAG) && shift && echo '#define MJIT_CFLAGS \\' && \
+	for w do echo '        "'$$w'", \\'; done; \
 	echo ' /* MJIT_CFLAGS */'; \
 	\
-	set x $(optflags) && shift && echo '#define MJIT_OPTFLAGS "'$$1'"' \\; \
-	shift && for w do echo ' , "'$$w'"' \\; done; \
+	set x $(optflags) && shift && echo '#define MJIT_OPTFLAGS \\' && \
+	for w do echo '        "'$$w'", \\'; done; \
 	echo ' /* MJIT_OPTFLAGS */'; \
 	\
-	set x $(debugflags) && shift && echo '#define MJIT_DEBUGFLAGS "'$$1'"' \\; \
-	shift && for w do echo ' , "'$$w'"' \\; done; \
+	set x $(debugflags) && shift && echo '#define MJIT_DEBUGFLAGS \\' && \
+	for w do echo '        "'$$w'", \\'; done; \
 	echo ' /* MJIT_DEBUGFLAGS */'; \
 	\
-	set x @LDSHARED@ && shift && echo '#define MJIT_LDSHARED "'$$1'"' \\; \
-	shift && for w do echo ' , "'$$w'"' \\; done; \
+	set x @LDSHARED@ && shift && echo '#define MJIT_LDSHARED \\' && \
+	for w do echo '        "'$$w'", \\'; done; \
 	echo ' /* MJIT_LDSHARED */'; \
 	\
-	set x @DLDFLAGS@ && shift && echo '#define MJIT_DLDFLAGS "'$$1'"' \\; \
-	shift && for w do echo ' , "'$$w'"' \\; done; \
+	set x @DLDFLAGS@ && shift && echo '#define MJIT_DLDFLAGS \\' && \
+	for w do echo '        "'$$w'", \\'; done; \
 	echo ' /* MJIT_DLDFLAGS */'; \
 	\
 	echo '#endif /* RUBY_MJIT_CONFIG_H */'; \
diff --git a/mjit.c b/mjit.c
index cb1cad0e9e..3152a427b0 100644
--- a/mjit.c
+++ b/mjit.c
@@ -561,9 +561,6 @@ free_list(struct rb_mjit_unit_list *list)
 }
 
 #include "mjit_config.h"
-#ifndef MJIT_CC
-#define MJIT_CC "cc"
-#endif
 
 /* XXX_COMMONN_ARGS define the command line arguments of XXX C
    compiler used by MJIT.
@@ -573,11 +570,11 @@ free_list(struct rb_mjit_unit_list *list)
 
    XXX_USE_PCH_ARAGS define additional options to use the precomiled
    header.  */
-static const char *const CC_DEBUG_ARGS[] = {MJIT_DEBUGFLAGS, NULL};
-static const char *const CC_OPTIMIZE_ARGS[] = {MJIT_OPTFLAGS, NULL};
+static const char *const CC_DEBUG_ARGS[] = {MJIT_DEBUGFLAGS NULL};
+static const char *const CC_OPTIMIZE_ARGS[] = {MJIT_OPTFLAGS NULL};
 
 static const char *const CC_COMMON_ARGS[] = {
-    MJIT_CC_COMMON, MJIT_CFLAGS,
+    MJIT_CC_COMMON MJIT_CFLAGS
 #if defined __GNUC__ && !defined __clang__
     "-Wfatal-errors", "-fPIC", "-shared", "-w",
     "-pipe", "-nostartfiles", "-nodefaultlibs", "-nostdlib",
@@ -585,11 +582,8 @@ static const char *const CC_COMMON_ARGS[] = {
     NULL
 };
 
-static const char *const CC_LDSHARED_ARGS[] = {MJIT_LDSHARED, NULL};
-static const char *const CC_DLDFLAGS_ARGS[] = {
-    MJIT_DLDFLAGS,
-    NULL
-};
+static const char *const CC_LDSHARED_ARGS[] = {MJIT_LDSHARED NULL};
+static const char *const CC_DLDFLAGS_ARGS[] = {MJIT_DLDFLAGS NULL};
 
 #ifdef __clang__
 static const char GCC_USE_PCH_ARGS[] = "-include-pch";
diff --git a/win32/Makefile.sub b/win32/Makefile.sub
index b707500f32..9500ca83cc 100644
--- a/win32/Makefile.sub
+++ b/win32/Makefile.sub
@@ -1250,27 +1250,27 @@ mjit_config.h:
 <<KEEP
 	@
 	@(set sep=#define MJIT_CC_COMMON ) & \
-	for %I in ($(CC)) do @(call echo.%%sep%%"%%~I" \& set sep= ,) >> $@
+	for %I in ($(CC)) do @(call echo.%%sep%%"%%~I", \& set sep= ) >> $@
 	@echo /* MJIT_CC_COMMON */>> $@
 	@
 	@(set sep=#define MJIT_CFLAGS ) & \
-	for %I in ($(RUNTIMEFLAG) $(ARCH_FLAG)) do @(call echo.%%sep%%"%%~I" \& set sep= ,) >> $@
+	for %I in ($(RUNTIMEFLAG) $(ARCH_FLAG)) do @(call echo.%%sep%%"%%~I", \& set sep= ) >> $@
 	@echo /* MJIT_CFLAGS */>> $@
 	@
 	@(set sep=#define MJIT_OPTFLAGS ) & \
-	for %I in ($(OPTFLAGS)) do @(call echo.%%sep%%"%%~I" \& set sep= ,) >> $@
+	for %I in ($(OPTFLAGS)) do @(call echo.%%sep%%"%%~I" \& set sep= ) >> $@
 	@echo /* MJIT_OPTFLAGS */>> $@
 	@
 	@(set sep=#define MJIT_DEBUGFLAGS ) & \
-	for %I in ($(DEBUGFLAGS)) do @(call echo.%%sep%%"%%~I" \& set sep= ,) >> $@
+	for %I in ($(DEBUGFLAGS)) do @(call echo.%%sep%%"%%~I", \& set sep= ) >> $@
 	@echo /* MJIT_DEBUGFLAGS */>> $@
 	@
 	@(set sep=#define MJIT_LDSHARED ) & \
-	for %I in ($(LDSHARED)) do @(call echo.%%sep%%"%%~I" \& set sep= ,) >> $@
+	for %I in ($(LDSHARED)) do @(call echo.%%sep%%"%%~I", \& set sep= ) >> $@
 	@echo /* MJIT_LDSHARED */>> $@
 	@
 	@(set sep=#define MJIT_DLDFLAGS ) & \
-	for %I in ($(DLDFLAGS)) do @(call echo.%%sep%%"%%~I" \& set sep= ,) >> $@
+	for %I in ($(DLDFLAGS)) do @(call echo.%%sep%%"%%~I", \& set sep= ) >> $@
 	@echo /* MJIT_DLDFLAGS */>> $@
 	@
 	@echo #endif /* RUBY_MJIT_CONFIG_H */>> $@