diff --git a/icu4c/source/common/ulocale.cpp b/icu4c/source/common/ulocale.cpp
index aaa17954a393..f2f81bc97109 100644
--- a/icu4c/source/common/ulocale.cpp
+++ b/icu4c/source/common/ulocale.cpp
@@ -21,7 +21,10 @@ U_NAMESPACE_USE
 ULocale*
 ulocale_openForLocaleID(const char* localeID, int32_t length, UErrorCode* err) {
     if (U_FAILURE(*err)) { return nullptr; }
-    CharString str(length < 0 ? StringPiece(localeID) : StringPiece(localeID, length), *err);
+    if (length < 0) {
+        return EXTERNAL(icu::Locale::createFromName(localeID).clone());
+    }
+    CharString str(localeID, length, *err);  // Make a NUL terminated copy.
     if (U_FAILURE(*err)) { return nullptr; }
     return EXTERNAL(icu::Locale::createFromName(str.data()).clone());
 }