diff --git a/icu4c/source/test/cintltst/cregrtst.c b/icu4c/source/test/cintltst/cregrtst.c
index 45a99373204..f6c5475f213 100644
--- a/icu4c/source/test/cintltst/cregrtst.c
+++ b/icu4c/source/test/cintltst/cregrtst.c
@@ -1604,7 +1604,7 @@ void doBreakInvariantTest(UBreakIteratorType type, UChar* testChars)
     UBreakIterator *tb;
     UTextOffset i, j;
     UErrorCode status = U_ZERO_ERROR;
-    UChar work[3]; 
+    UChar work[4]; 
     UChar breaks[10];
     UChar c;
     UChar *ustr;