diff --git a/deps/icu-small/README-SMALL-ICU.txt b/deps/icu-small/README-SMALL-ICU.txt
index 1f524e36113af0..b1aeabe031187c 100644
--- a/deps/icu-small/README-SMALL-ICU.txt
+++ b/deps/icu-small/README-SMALL-ICU.txt
@@ -3,6 +3,6 @@ Small ICU sources - auto generated by shrink-icu-src.py
 This directory contains the ICU subset used by --with-intl=small-icu (the default)
 It is a strict subset of ICU 67 source files with the following exception(s):
 * deps/icu-small/source/data/in/icudt67l.dat : Reduced-size data file
-
+* deps/icu-small/source/common/uassert.h : Manual backport of ICU-21081
 
 To rebuild this directory, see ../../tools/icu/README.md
diff --git a/deps/icu-small/source/common/uassert.h b/deps/icu-small/source/common/uassert.h
index 15cd55c873487c..afd31eeffd91a4 100644
--- a/deps/icu-small/source/common/uassert.h
+++ b/deps/icu-small/source/common/uassert.h
@@ -32,7 +32,7 @@
 #   include <assert.h>
 #   define U_ASSERT(exp) assert(exp)
 #elif U_CPLUSPLUS_VERSION
-#   define U_ASSERT(exp) void()
+#   define U_ASSERT(exp) (void)0
 #else
 #   define U_ASSERT(exp)
 #endif