diff --git a/icu4c/source/io/unicode/ustdio.h b/icu4c/source/io/unicode/ustdio.h
index 5aad6b9bbead..bdfcb35e65f4 100644
--- a/icu4c/source/io/unicode/ustdio.h
+++ b/icu4c/source/io/unicode/ustdio.h
@@ -713,8 +713,8 @@ u_fgetc(UFILE   *f);
  *
  * @param f The UFILE from which to read.
  * @return The UChar32 value read, or U_EOF if no character was
- * available, or U+FFFFFFFF if an ill-formed character was
- * encountered.
+ * available, or U+FFFD (replacement character) if an ill-formed
+ * character was encountered.
  * @see u_unescape()
  * @stable ICU 3.0
  */