diff --git a/elisp/proto/BUILD b/elisp/proto/BUILD
index 3678f02c..ce709e6a 100644
--- a/elisp/proto/BUILD
+++ b/elisp/proto/BUILD
@@ -168,6 +168,7 @@ cc_binary(
         "@com_google_absl//absl/base:config",
         "@com_google_absl//absl/base:core_headers",
         "@upb",
+        "@upb//:base",
         "@upb//:collections",
         "@upb//:descriptor_upb_proto",
         "@upb//:json",
diff --git a/elisp/proto/module.c b/elisp/proto/module.c
index 63ac806e..090eeb28 100644
--- a/elisp/proto/module.c
+++ b/elisp/proto/module.c
@@ -149,6 +149,7 @@
 #include "google/protobuf/duration.upbdefs.h"
 #include "google/protobuf/timestamp.upb.h"
 #include "google/protobuf/timestamp.upbdefs.h"
+#include "upb/base/upcast.h"
 #include "upb/collections.h"
 #include "upb/decode.h"
 #include "upb/def.h"
@@ -3528,8 +3529,10 @@ static emacs_value Timestamp(emacs_env* env,
                                                   kTimestampP, args[0]);
   if (msg.type == NULL) return NULL;
   struct timespec time;
-  time.tv_sec = google_protobuf_Timestamp_seconds(msg.value);
-  time.tv_nsec = google_protobuf_Timestamp_nanos(msg.value);
+  time.tv_sec = google_protobuf_Timestamp_seconds(
+      (google_protobuf_Timestamp*)msg.value);
+  time.tv_nsec = google_protobuf_Timestamp_nanos(
+      (google_protobuf_Timestamp*)msg.value);
   return MakeTime(ctx, time);
 }
 
@@ -3542,8 +3545,10 @@ static emacs_value Duration(emacs_env* env,
                                                   kDurationP, args[0]);
   if (msg.type == NULL) return NULL;
   struct timespec time;
-  time.tv_sec = google_protobuf_Duration_seconds(msg.value);
-  time.tv_nsec = google_protobuf_Duration_nanos(msg.value);
+  time.tv_sec = google_protobuf_Duration_seconds(
+      (google_protobuf_Duration*)msg.value);
+  time.tv_nsec = google_protobuf_Duration_nanos(
+      (google_protobuf_Duration*)msg.value);
   return MakeTime(ctx, time);
 }
 
@@ -3556,7 +3561,7 @@ static emacs_value SetTimestamp(emacs_env* env,
       ctx, kUpb_WellKnown_Timestamp, kTimestampP, args[0]);
   if (msg.type == NULL) return NULL;
   emacs_value time = args[1];
-  SetTimestampProto(ctx, msg.value, time);
+  SetTimestampProto(ctx, (google_protobuf_Timestamp*)msg.value, time);
   return time;
 }
 
@@ -3569,7 +3574,7 @@ static emacs_value SetDuration(emacs_env* env,
       ctx, kUpb_WellKnown_Duration, kDurationP, args[0]);
   if (msg.type == NULL) return NULL;
   emacs_value time = args[1];
-  SetDurationProto(ctx, msg.value, time);
+  SetDurationProto(ctx, (google_protobuf_Duration*)msg.value, time);
   return time;
 }
 
@@ -3589,7 +3594,7 @@ static emacs_value MakeTimestamp(emacs_env* env,
   }
   if (!SetTimestampProto(ctx, msg, args[0])) return NULL;
   return MakeMessageStruct(ctx, arena, GlobalSymbol(ctx, kTimestampNew), def,
-                           msg, true);
+                           UPB_UPCAST(msg), true);
 }
 
 static emacs_value MakeDuration(emacs_env* env,
@@ -3608,7 +3613,7 @@ static emacs_value MakeDuration(emacs_env* env,
   }
   if (!SetDurationProto(ctx, msg, args[0])) return NULL;
   return MakeMessageStruct(ctx, arena, GlobalSymbol(ctx, kDurationNew), def,
-                           msg, true);
+                           UPB_UPCAST(msg), true);
 }
 
 static emacs_value PackAny(emacs_env* env,
@@ -3635,7 +3640,7 @@ static emacs_value PackAny(emacs_env* env,
   if (type_url.data == NULL || serialized.data == NULL) return NULL;
   google_protobuf_Any_set_type_url(any, View(type_url));
   google_protobuf_Any_set_value(any, View(serialized));
-  return MakeMutableMessage(ctx, arena, any_def, any);
+  return MakeMutableMessage(ctx, arena, any_def, UPB_UPCAST(any));
 }
 
 static emacs_value UnpackAny(emacs_env* env,
@@ -3647,8 +3652,10 @@ static emacs_value UnpackAny(emacs_env* env,
   struct MessageArg any =
       ExtractWellKnownMessage(ctx, kUpb_WellKnown_Any, kAnyP, arg);
   if (any.type == NULL) return NULL;
-  upb_StringView type_url = google_protobuf_Any_type_url(any.value);
-  upb_StringView serialized = google_protobuf_Any_value(any.value);
+  upb_StringView type_url = google_protobuf_Any_type_url(
+      (google_protobuf_Any *)any.value);
+  upb_StringView serialized = google_protobuf_Any_value(
+      (google_protobuf_Any *)any.value);
   if (type_url.data == NULL || serialized.data == NULL) {
     UninitializedAny(ctx, arg);
     return NULL;
@@ -3670,7 +3677,8 @@ static emacs_value AnyTypeName(emacs_env* env,
   struct MessageArg any =
       ExtractWellKnownMessage(ctx, kUpb_WellKnown_Any, kAnyP, arg);
   if (any.type == NULL) return NULL;
-  upb_StringView type_url = google_protobuf_Any_type_url(any.value);
+  upb_StringView type_url = google_protobuf_Any_type_url(
+      (google_protobuf_Any *)any.value);
   if (type_url.data == NULL) {
     UninitializedAny(ctx, arg);
     return NULL;