diff --git a/upb/mini_table/extension_registry.h b/upb/mini_table/extension_registry.h
index 387dd09e49..fb7ba053c2 100644
--- a/upb/mini_table/extension_registry.h
+++ b/upb/mini_table/extension_registry.h
@@ -76,7 +76,7 @@ typedef struct upb_ExtensionRegistry upb_ExtensionRegistry;
 
 // Creates a upb_ExtensionRegistry in the given arena.
 // The arena must outlive any use of the extreg.
-upb_ExtensionRegistry* upb_ExtensionRegistry_New(upb_Arena* arena);
+UPB_API upb_ExtensionRegistry* upb_ExtensionRegistry_New(upb_Arena* arena);
 
 // Adds the given extension info for the array |e| of size |count| into the
 // registry. If there are any errors, the entire array is backed out.
diff --git a/upb/wire/decode.h b/upb/wire/decode.h
index 31eee25070..e4423598d4 100644
--- a/upb/wire/decode.h
+++ b/upb/wire/decode.h
@@ -80,10 +80,10 @@ typedef enum {
   kUpb_DecodeStatus_MissingRequired = 5,
 } upb_DecodeStatus;
 
-upb_DecodeStatus upb_Decode(const char* buf, size_t size, upb_Message* msg,
-                            const upb_MiniTable* l,
-                            const upb_ExtensionRegistry* extreg, int options,
-                            upb_Arena* arena);
+UPB_API upb_DecodeStatus upb_Decode(const char* buf, size_t size,
+                                    upb_Message* msg, const upb_MiniTable* l,
+                                    const upb_ExtensionRegistry* extreg,
+                                    int options, upb_Arena* arena);
 
 #ifdef __cplusplus
 } /* extern "C" */