diff --git a/tests/conformance_upb_failures.txt b/tests/conformance_upb_failures.txt
index 33c013d927..05aab585e7 100644
--- a/tests/conformance_upb_failures.txt
+++ b/tests/conformance_upb_failures.txt
@@ -1,15 +1 @@
-Recommended.ProtobufInput.OneofZeroBool.ProtobufOutput
-Recommended.ProtobufInput.OneofZeroBytes.ProtobufOutput
-Recommended.ProtobufInput.OneofZeroDouble.ProtobufOutput
-Recommended.ProtobufInput.OneofZeroEnum.ProtobufOutput
-Recommended.ProtobufInput.OneofZeroFloat.ProtobufOutput
-Recommended.ProtobufInput.OneofZeroString.ProtobufOutput
-Recommended.ProtobufInput.OneofZeroUint32.ProtobufOutput
-Recommended.ProtobufInput.OneofZeroUint64.ProtobufOutput
 Required.ProtobufInput.PrematureEofInSubmessageValue.MESSAGE
-Required.ProtobufInput.RepeatedScalarSelectsLast.BOOL.ProtobufOutput
-Required.ProtobufInput.RepeatedScalarSelectsLast.FIXED32.ProtobufOutput
-Required.ProtobufInput.RepeatedScalarSelectsLast.FIXED64.ProtobufOutput
-Required.ProtobufInput.RepeatedScalarSelectsLast.UINT64.ProtobufOutput
-Required.ProtobufInput.ValidDataRepeated.BOOL.ProtobufOutput
-Required.ProtobufInput.ValidDataScalar.BOOL.ProtobufOutput
diff --git a/upb/decode.c b/upb/decode.c
index a1910a1a0d..3a44021829 100644
--- a/upb/decode.c
+++ b/upb/decode.c
@@ -309,6 +309,11 @@ static bool upb_decode_varintfield(upb_decstate *d, upb_decframe *frame,
       memcpy(field_mem, &val32, sizeof(val32));
       break;
     }
+    case UPB_DESCRIPTOR_TYPE_BOOL: {
+      bool valbool = val != 0;
+      memcpy(field_mem, &valbool, sizeof(valbool));
+      break;
+    }
     case UPB_DESCRIPTOR_TYPE_SINT32: {
       int32_t decoded = upb_zzdec_32(val);
       memcpy(field_mem, &decoded, sizeof(decoded));
diff --git a/upb/encode.c b/upb/encode.c
index 8a220ef6e2..4aafb9c1c5 100644
--- a/upb/encode.c
+++ b/upb/encode.c
@@ -258,7 +258,7 @@ static bool upb_encode_scalarfield(upb_encstate *e, const char *field_mem,
                                    bool is_proto3) {
 #define CASE(ctype, type, wire_type, encodeval) do { \
   ctype val = *(ctype*)field_mem; \
-  if (is_proto3 && val == 0) { \
+  if (is_proto3 && f->oneof_index == UPB_NOT_IN_ONEOF && val == 0) { \
     return true; \
   } \
   return upb_put_ ## type(e, encodeval) && \
@@ -292,7 +292,7 @@ static bool upb_encode_scalarfield(upb_encstate *e, const char *field_mem,
     case UPB_DESCRIPTOR_TYPE_STRING:
     case UPB_DESCRIPTOR_TYPE_BYTES: {
       upb_stringview view = *(upb_stringview*)field_mem;
-      if (is_proto3 && view.size == 0) {
+      if (is_proto3 && f->oneof_index == UPB_NOT_IN_ONEOF && view.size == 0) {
         return true;
       }
       return upb_put_bytes(e, view.data, view.size) &&
@@ -303,7 +303,7 @@ static bool upb_encode_scalarfield(upb_encstate *e, const char *field_mem,
       size_t size;
       void *submsg = *(void**)field_mem;
       const upb_msglayout_msginit_v1 *subm = m->submsgs[f->submsg_index];
-      if (is_proto3 && submsg == NULL) {
+      if (is_proto3 && f->oneof_index == UPB_NOT_IN_ONEOF && submsg == NULL) {
         return true;
       }
       return upb_put_tag(e, f->number, UPB_WIRE_TYPE_END_GROUP) &&
@@ -314,7 +314,7 @@ static bool upb_encode_scalarfield(upb_encstate *e, const char *field_mem,
       size_t size;
       void *submsg = *(void**)field_mem;
       const upb_msglayout_msginit_v1 *subm = m->submsgs[f->submsg_index];
-      if (is_proto3 && submsg == NULL) {
+      if (is_proto3 && f->oneof_index == UPB_NOT_IN_ONEOF && submsg == NULL) {
         return true;
       }
       return upb_encode_message(e, submsg, subm, &size) &&
@@ -344,6 +344,11 @@ bool upb_encode_message(upb_encstate* e, const char *msg,
                         size_t *size) {
   int i;
   char *buf_end = e->ptr;
+
+  if (msg == NULL) {
+    return true;
+  }
+
   for (i = m->field_count - 1; i >= 0; i--) {
     const upb_msglayout_fieldinit_v1 *f = &m->fields[i];