diff --git a/icu4c/source/common/uassert.h b/icu4c/source/common/uassert.h
index 15cd55c87348..afd31eeffd91 100644
--- a/icu4c/source/common/uassert.h
+++ b/icu4c/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