diff --git a/icu4c/source/i18n/timezone.cpp b/icu4c/source/i18n/timezone.cpp
index fcf5f6f22d..82228e1731 100644
--- a/icu4c/source/i18n/timezone.cpp
+++ b/icu4c/source/i18n/timezone.cpp
@@ -1592,6 +1592,7 @@ TimeZone::getWindowsID(const UnicodeString& id, UnicodeString& winid, UErrorCode
         ures_close(regionalData);
     }
     ures_close(winzone);
+    ures_close(mapTimezones);
 
     return winid;
 }