diff -Nru orig/Rhpc/src/Makevars.ucrt patched/Rhpc/src/Makevars.ucrt
--- orig/Rhpc/src/Makevars.ucrt	1969-12-31 16:00:00.000000000 -0800
+++ patched/Rhpc/src/Makevars.ucrt	2021-02-18 02:54:04.606719500 -0800
@@ -0,0 +1,52 @@
+MPI_TYPE=MSMPI
+ifeq "$(MPI_TYPE)" "MSMPI"
+XMSMPI_INC='$(subst \,/,$(MSMPI_INC))'
+XMSMPI_LIB32='$(subst \,/,$(MSMPI_LIB32))'
+XMSMPI_LIB64='$(subst \,/,$(MSMPI_LIB64))'
+
+ifeq "$(WIN)" "64"
+ARCH=amd64
+NM=nm
+MPILIBA=-lmsmpi
+PKG_CFLAGS= -I$(XMSMPI_INC) -DMSMPI_NO_DEPRECATE_20
+#PKG_LIBS= "$(XMSMPI_LIB64)/msmpi.lib" -ladvapi32
+PKG_LIBS= $(MPILIBA) -ladvapi32 
+else
+ARCH=i386
+NM=nm
+MPILIBA=libmsmpi32.a
+PKG_CFLAGS= -I$(XMSMPI_INC) -DMSMPI_NO_DEPRECATE_20
+PKG_LIBS= -L$(XMSMPI_LIB32) -l:msmpi.lib -ladvapi32
+endif
+endif
+
+SUBDIRS = worker
+SOURCES_C = RhpcMPI.c RhpcSerialize.c registerDynamicSymbol.c
+OBJECTS = $(SOURCES_C:.c=.o)
+MKCONF = $(R_HOME)/etc$(R_ARCH)/Makeconf
+
+ifeq "$(WIN)" "64"
+all: $(SHLIB) subdirs
+else
+all: $(SHLIB) subdirs
+endif
+
+$(SHLIB): $(OBJECTS)
+
+clean: subdirsclean
+	@-rm -f $(OBJECTS) $(SHLIB) libmsmpi64.a msmpi64.def
+
+subdirs: subdirsclean
+	@for d in $(SUBDIRS); do \
+		(cd $${d} && echo $(MAKE) -f Makefile.ucrt -f $(MKCONF) )|| exit 1;\
+	done
+	@for d in $(SUBDIRS); do \
+		(cd $${d} && $(MAKE) -f Makefile.ucrt -f $(MKCONF) )|| exit 1;\
+	done
+
+subdirsclean:
+	@for d in $(SUBDIRS); do \
+		(cd $${d} && $(MAKE) -f Makefile.ucrt MKCONF=$(MKCONF) clean)|| exit 1; \
+	done
+
+
diff -Nru orig/Rhpc/src/worker/Makefile.ucrt patched/Rhpc/src/worker/Makefile.ucrt
--- orig/Rhpc/src/worker/Makefile.ucrt	1969-12-31 16:00:00.000000000 -0800
+++ patched/Rhpc/src/worker/Makefile.ucrt	2021-02-18 02:55:23.059494400 -0800
@@ -0,0 +1,59 @@
+
+MPI_TYPE=MSMPI
+ifeq "$(MPI_TYPE)" "MSMPI"
+XMSMPI_INC='$(subst \,/,$(MSMPI_INC))'
+XMSMPI_LIB32='$(subst \,/,$(MSMPI_LIB32))'
+XMSMPI_LIB64='$(subst \,/,$(MSMPI_LIB64))'
+ifeq "$(WIN)" "64"
+TARGET_ARCH=64
+MPILIBA=-lmsmpi
+PKG_CFLAGS= -I$(XMSMPI_INC) -DMSMPI_NO_DEPRECATE_20
+#PKG_LIBS= "$(XMSMPI_LIB64)/msmpi.lib"
+PKG_LIBS= $(MPILIBA)
+else
+TARGET_ARCH=32
+PKG_CFLAGS= -I$(XMSMPI_INC) -DMSMPI_NO_DEPRECATE_20
+PKG_LIBS= -L$(XMSMPI_LIB32) -l:msmpi.lib
+endif
+endif
+
+CP = cp
+SOURCES_C=RhpcWorker.c RhpcWorkerSerialize.c
+OBJECTS=$(SOURCES_C:.c=.o)
+
+
+all:	RhpcWorker$(TARGET_ARCH).exe fakemaster$(TARGET_ARCH).exe RhpcWin$(TARGET_ARCH).cmd Rhpc$(TARGET_ARCH).cmd RhpcSpawnWin$(TARGET_ARCH).cmd
+	@echo $(CP) -p RhpcWorker$(TARGET_ARCH).exe $(R_PACKAGE_DIR)
+	@$(CP) -p RhpcWorker$(TARGET_ARCH).exe $(R_PACKAGE_DIR)
+	@echo $(CP) -p fakemaster$(TARGET_ARCH).exe $(R_PACKAGE_DIR)
+	@$(CP) -p fakemaster$(TARGET_ARCH).exe $(R_PACKAGE_DIR)
+	@$(CP) -p RhpcWin$(TARGET_ARCH).cmd $(R_PACKAGE_DIR)
+	@$(CP) -p Rhpc$(TARGET_ARCH).cmd $(R_PACKAGE_DIR)
+	@$(CP) -p RhpcSpawnWin$(TARGET_ARCH).cmd $(R_PACKAGE_DIR)
+
+RhpcWin$(TARGET_ARCH).cmd: RhpcWin.cmd.in
+	$(SED) -b -e 's/@@ARCH@@/$(TARGET_ARCH)/g' < RhpcWin.cmd.in > $@
+
+Rhpc$(TARGET_ARCH).cmd: Rhpc.cmd.in
+	$(SED) -b -e 's/@@ARCH@@/$(TARGET_ARCH)/g' < Rhpc.cmd.in > $@
+
+RhpcSpawnWin$(TARGET_ARCH).cmd: RhpcSpawnWin.cmd.in
+	$(SED) -b -e 's/@@ARCH@@/$(TARGET_ARCH)/g' < RhpcSpawnWin.cmd.in > $@
+
+RhpcWorker$(TARGET_ARCH).exe: $(OBJECTS)
+	$(CC) $(ALL_CPPFLAGS) $(ALL_CFLAGS) $(OBJECTS) -o $@ $(PKG_LIBS) $(LIBR)
+
+RhpcWorker.o: RhpcWorker.c
+	$(CC) $(ALL_CPPFLAGS) $(ALL_CFLAGS) $(PKG_CFLAGS) -c $< -o $@
+
+fakemaster$(TARGET_ARCH).exe: fakemaster$(TARGET_ARCH).o
+	$(CC) $(ALL_CPPFLAGS) $(ALL_CFLAGS) $< -o $@
+
+fakemaster$(TARGET_ARCH).o: fakemaster.c
+	$(CC) $(ALL_CPPFLAGS) $(ALL_CFLAGS) -c $< -o $@
+
+RhpcSerialize.o: RhpcWorkerSerialize.c
+	$(CC) $(ALL_CPPFLAGS) $(ALL_CFLAGS) $(PKG_CFLAGS) -c $< -o $@
+
+clean:
+	@-$(RM) -f RhpcWorker RhpcWorker32.exe RhpcWorker64.exe RhpcWin32.cmd RhpcWin64.cmd RhpcSpawnWin32.cmd RhpcSpawnWin64.cmd $(OBJECTS) fakemaster*.o fakemaster*.exe