diff --git a/upb/port/def.inc b/upb/port/def.inc
index f66885ddf55cf..1305fd164b293 100644
--- a/upb/port/def.inc
+++ b/upb/port/def.inc
@@ -534,7 +534,7 @@ Error, UINTPTR_MAX is undefined
 #define UPB_LINKARR_DECLARE(name, type) \
   extern type __start_linkarr_##name;   \
   extern type __stop_linkarr_##name;    \
-  UPB_LINKARR_APPEND(name)              \
-  UPB_LINKARR_SENTINEL type UPB_linkarr_internal_empty_##name[1]
+  UPB_LINKARR_APPEND(name)                                          \
+  UPB_LINKARR_SENTINEL type UPB_linkarr_internal_empty_##name[1] = {0}
 #define UPB_LINKARR_START(name) (&__start_linkarr_##name)
 #define UPB_LINKARR_STOP(name) (&__stop_linkarr_##name)
 
@@ -554,7 +554,7 @@ Error, UINTPTR_MAX is undefined
   extern type __stop_linkarr_##name __asm(  \
       "section$end$__DATA$"                 \
       "__la_" #name);                       \
-  UPB_LINKARR_APPEND(name)                  \
-  UPB_LINKARR_SENTINEL type UPB_linkarr_internal_empty_##name[1]
+  UPB_LINKARR_APPEND(name)                                              \
+  UPB_LINKARR_SENTINEL type UPB_linkarr_internal_empty_##name[1] = {0}
 #define UPB_LINKARR_START(name) (&__start_linkarr_##name)
 #define UPB_LINKARR_STOP(name) (&__stop_linkarr_##name)
 
@@ -570,7 +570,7 @@ Error, UINTPTR_MAX is undefined
 
 #define UPB_LINKARR_ATTR
 
-#define UPB_LINKARR_SENTINEL UPB_RETAIN __attribute__((weak, used))
+#define UPB_LINKARR_SENTINEL __attribute__((weak, used))
 
 #if defined(__ELF__) || defined(__wasm__)