diff --git a/ChangeLog b/ChangeLog
index 7d1c5ab2ea063744967e811242bab9cc6c880070..6ad18d97922849751e979a95c5bdc6f7a3c7959c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -5,6 +5,7 @@
 
 2024-10-24  Uwe Schulzweida
 
+	* lock access to NCZARR in CDI_Threadsafe mode
 	* Renamed interface functions streamXXXRecord to streamXXXField
 
 2024-10-22  Uwe Schulzweida
diff --git a/src/stream.c b/src/stream.c
index 8ebd6be67f58a15144661505f6d1f7bed42bda93..7264d353566a1e94c0ab55bec832444762c379f8 100644
--- a/src/stream.c
+++ b/src/stream.c
@@ -674,7 +674,8 @@ streamOpenID(const char *filename, char filemode, int filetype, int resH)
 #ifndef HAVE_LIBPTHREAD
       Error("CDI threadsafe failed, pthread support not compiled in!");
 #endif
-      if (filetype == CDI_FILETYPE_NC4 || filetype == CDI_FILETYPE_NC4C) streamptr->lockIO = true;
+      if (filetype == CDI_FILETYPE_NC4 || filetype == CDI_FILETYPE_NC4C || filetype == CDI_FILETYPE_NCZARR)
+        streamptr->lockIO = true;
     }
 #endif