diff --git a/dlls/msi/package.c b/dlls/msi/package.c
index 63377a0532e..18466e1b995 100644
--- a/dlls/msi/package.c
+++ b/dlls/msi/package.c
@@ -2282,7 +2282,7 @@ static MSIRECORD *msi_get_property_row( MSIDATABASE *db, LPCWSTR name )
         if (!length)
             return NULL;
         buffer = msi_alloc(length * sizeof(WCHAR));
-        GetDateFormatW(LOCALE_USER_DEFAULT, DATE_SHORTDATE, NULL, NULL, buffer, sizeof(WCHAR));
+        GetDateFormatW(LOCALE_USER_DEFAULT, DATE_SHORTDATE, NULL, NULL, buffer, length);
 
         row = MSI_CreateRecord(1);
         if (!row)
@@ -2297,7 +2297,7 @@ static MSIRECORD *msi_get_property_row( MSIDATABASE *db, LPCWSTR name )
         if (!length)
             return NULL;
         buffer = msi_alloc(length * sizeof(WCHAR));
-        GetTimeFormatW(LOCALE_USER_DEFAULT, TIME_NOTIMEMARKER, NULL, NULL, buffer, sizeof(WCHAR));
+        GetTimeFormatW(LOCALE_USER_DEFAULT, TIME_NOTIMEMARKER, NULL, NULL, buffer, length);
 
         row = MSI_CreateRecord(1);
         if (!row)