diff --git a/icu4c/source/data/Makefile.in b/icu4c/source/data/Makefile.in
index c9c900d2fe7..49dc2a0c6ce 100644
--- a/icu4c/source/data/Makefile.in
+++ b/icu4c/source/data/Makefile.in
@@ -313,7 +313,7 @@ $(TESTBUILDDIR)/testdata.lst: $(SRCLISTDEPS)
 	done;
 
 
-build-testdata:  $(ALL_TEST_FILES) $(TESTBUILDDIR)/testdata.lst $(TESTBUILDDIR)/$(TESTDT)ja_data.res
+build-testdata:  $(ALL_TEST_FILES) $(TESTBUILDDIR)/testdata.lst $(TESTBUILDDIR)/$(TESTDT)iscii.res
 
 # test.icu
 $(TESTBUILDDIR)/$(TESTDT)test.icu: $(TOOLDIR)/gentest/gentest$(EXEEXT)
@@ -326,8 +326,8 @@ $(TESTBUILDDIR)/$(TESTDT)%.res: $(TESTSRCDATADIR)/%.txt $(TOOLDIR)/genrb/genrb$(
 	ICU_DATA=$(BUILDDIR) $(INVOKE) $(TOOLDIR)/genrb/genrb $(GENRBOPTS) -p $(TESTDATA) -q -s $(TESTSRCDATADIR) -d $(TESTBUILDDIR) $(<F)
 
 
-$(TESTBUILDDIR)/$(TESTDT)ja_data.res:  $(TESTSRCDATADIR)/ja_data.bin $(TOOLDIR)/genrb/genrb$(EXEEXT)
-	ICU_DATA=$(BUILDDIR) $(INVOKE) $(TOOLDIR)/genrb/genrb $(GENRBOPTS) -q -s $(TESTSRCDATADIR) -p $(TESTDATA) -eISO_2022_JP -d $(TESTBUILDDIR) $(<F) >/dev/null  
+$(TESTBUILDDIR)/$(TESTDT)iscii.res:  $(TESTSRCDATADIR)/iscii.bin $(TOOLDIR)/genrb/genrb$(EXEEXT)
+	ICU_DATA=$(BUILDDIR) $(INVOKE) $(TOOLDIR)/genrb/genrb $(GENRBOPTS) -q -s $(TESTSRCDATADIR) -p $(TESTDATA) -eISCII,version=0 -d $(TESTBUILDDIR) $(<F) >/dev/null  
 
 ################################################################### TYP
 # TYP FILES
diff --git a/icu4c/source/test/testdata/testdata.mk b/icu4c/source/test/testdata/testdata.mk
index b97f568b8a9..c5433a56e52 100644
--- a/icu4c/source/test/testdata/testdata.mk
+++ b/icu4c/source/test/testdata/testdata.mk
@@ -42,8 +42,8 @@ testdata_test4.cnv
 	@"$(ICUTOOLS)\genrb\$(CFG)\genrb" -t -p"$(TESTPKG)" -q -s"$(TESTDATA)" -d"$(TESTDATABLD)" $<
 
 "$(TESTDATABLD)\iscii.res":
-	@echo Making Test Resource Bundle file with encoding x-iscii-de
-	@"$(ICUTOOLS)\genrb\$(CFG)\genrb" -t -p"$(TESTPKG)" -q -s"$(TESTDATA)" -ex-iscii-de -d"$(TESTDATABLD)" iscii.bin 
+	@echo Making Test Resource Bundle file with encoding ISCII,version=0 
+	@"$(ICUTOOLS)\genrb\$(CFG)\genrb" -t -p"$(TESTPKG)" -q -s"$(TESTDATA)" -eISCII,version=0 -d"$(TESTDATABLD)" iscii.bin 
 
 $(TESTDATABLD)\testdata_test.icu : {"$(ICUTOOLS)\gentest\$(CFG)"}gentest.exe
 	"$(ICUTOOLS)\gentest\$(CFG)\gentest" -d"$(TESTDATABLD)"