diff -ur icu.org/source/data/Makefile.in icu/source/data/Makefile.in
--- icu.org/source/data/Makefile.in	2020-10-28 22:21:12.000000000 +0100
+++ icu/source/data/Makefile.in	2020-11-17 10:18:37.960032668 +0100
@@ -239,6 +239,13 @@
 
 ifeq ($(ENABLE_SO_VERSION_DATA),1)
 ifeq ($(PKGDATA_MODE),dll)
+
+# This should be in the included rules.mk but that is generated empty by
+# configure because we have no data/locales/root.txt with prebuilt data/in/
+$(TMP_DIR)/dirs.timestamp:
+	$(MKINSTALLDIRS) $(OUTTMPDIR) $(TMP_DIR)
+	echo timestamp > $@
+
 SO_VERSION_DATA = $(OUTTMPDIR)/icudata.res
 $(SO_VERSION_DATA) : $(MISCSRCDIR)/icudata.rc | $(TMP_DIR)/dirs.timestamp
 ifeq ($(MSYS_RC_MODE),1)