diff --git a/icu4c/source/data/BUILDRULES.py b/icu4c/source/data/BUILDRULES.py
index e6ddea9..063de7c 100644
--- a/icu4c/source/data/BUILDRULES.py
+++ b/icu4c/source/data/BUILDRULES.py
@@ -362,7 +362,7 @@
         RepeatedExecutionRequest(
             name = "misc_res",
             category = "misc",
-            dep_targets = [],
+            dep_targets = [DepTarget("cnvalias")], # ICU-21175
             input_files = input_files,
             output_files = output_files,
             tool = IcuTool("genrb"),