diff --git a/icu4c/source/test/perf/DateFmtPerf/DateFmtPerf.h b/icu4c/source/test/perf/DateFmtPerf/DateFmtPerf.h
index c9c239cd2d6e..b94b368b3cfe 100644
--- a/icu4c/source/test/perf/DateFmtPerf/DateFmtPerf.h
+++ b/icu4c/source/test/perf/DateFmtPerf/DateFmtPerf.h
@@ -632,7 +632,7 @@ class NumFmtFunction : public UPerfFunction
         case Formattable::kInt64:
             {
                 char buf[256];
-                sprintf(buf, "%ldL", f.getLong());
+                sprintf(buf, "%dL", f.getLong());
                 return UnicodeString(buf, "");
             }
         case Formattable::kString: