diff --git a/upbc/upbc_so.c b/upbc/upbc_so.c
index 6e498865be..b40b9b645a 100644
--- a/upbc/upbc_so.c
+++ b/upbc/upbc_so.c
@@ -40,3 +40,43 @@
 
 // Must be last.
 #include "upb/port/def.inc"
+
+// JavaScript doesn't directly support 64-bit ints so we must split them.
+
+UPB_API_INLINE uint32_t upb_Message_GetInt64Hi(const upb_Message* msg,
+                                               const upb_MiniTableField* field,
+                                               uint32_t default_value) {
+  return (uint32_t)(upb_Message_GetInt64(msg, field, default_value) >> 32);
+}
+
+UPB_API_INLINE uint32_t upb_Message_GetInt64Lo(const upb_Message* msg,
+                                               const upb_MiniTableField* field,
+                                               uint32_t default_value) {
+  return (uint32_t)upb_Message_GetInt64(msg, field, default_value);
+}
+
+UPB_API_INLINE bool upb_Message_SetInt64Split(upb_Message* msg,
+                                              const upb_MiniTableField* field,
+                                              uint32_t hi, uint32_t lo,
+                                              upb_Arena* a) {
+  return upb_Message_SetInt64(msg, field, ((int64_t)hi << 32) | lo, a);
+}
+
+UPB_API_INLINE uint32_t upb_Message_GetUInt64Hi(const upb_Message* msg,
+                                                const upb_MiniTableField* field,
+                                                uint32_t default_value) {
+  return (uint32_t)(upb_Message_GetUInt64(msg, field, default_value) >> 32);
+}
+
+UPB_API_INLINE uint32_t upb_Message_GetUInt64Lo(const upb_Message* msg,
+                                                const upb_MiniTableField* field,
+                                                uint32_t default_value) {
+  return (uint32_t)upb_Message_GetUInt64(msg, field, default_value);
+}
+
+UPB_API_INLINE bool upb_Message_SetUInt64Split(upb_Message* msg,
+                                               const upb_MiniTableField* field,
+                                               uint32_t hi, uint32_t lo,
+                                               upb_Arena* a) {
+  return upb_Message_SetUInt64(msg, field, ((uint64_t)hi << 32) | lo, a);
+}