diff --git a/lightning.pb-c.c b/lightning.pb-c.c
index ea177a553..49a14b5ac 100644
--- a/lightning.pb-c.c
+++ b/lightning.pb-c.c
@@ -1383,7 +1383,7 @@ const ProtobufCMessageDescriptor anchor__descriptor =
   (ProtobufCMessageInit) anchor__init,
   NULL,NULL,NULL    /* reserved[123] */
 };
-static const ProtobufCFieldDescriptor open_channel__field_descriptors[8] =
+static const ProtobufCFieldDescriptor open_channel__field_descriptors[7] =
 {
   {
     "seed",
@@ -1400,25 +1400,13 @@ static const ProtobufCFieldDescriptor open_channel__field_descriptors[8] =
   {
     "locktime_seconds",
     2,
-    PROTOBUF_C_LABEL_OPTIONAL,
+    PROTOBUF_C_LABEL_REQUIRED,
     PROTOBUF_C_TYPE_UINT32,
-    offsetof(OpenChannel, locktime_case),
+    0,   /* quantifier_offset */
     offsetof(OpenChannel, locktime_seconds),
     NULL,
     NULL,
-    0 | PROTOBUF_C_FIELD_FLAG_ONEOF,             /* flags */
-    0,NULL,NULL    /* reserved1,reserved2, etc */
-  },
-  {
-    "locktime_blocks",
-    3,
-    PROTOBUF_C_LABEL_OPTIONAL,
-    PROTOBUF_C_TYPE_UINT32,
-    offsetof(OpenChannel, locktime_case),
-    offsetof(OpenChannel, locktime_blocks),
-    NULL,
-    NULL,
-    0 | PROTOBUF_C_FIELD_FLAG_ONEOF,             /* flags */
+    0,             /* flags */
     0,NULL,NULL    /* reserved1,reserved2, etc */
   },
   {
@@ -1483,19 +1471,19 @@ static const ProtobufCFieldDescriptor open_channel__field_descriptors[8] =
   },
 };
 static const unsigned open_channel__field_indices_by_name[] = {
-  6,   /* field[6] = anchor */
-  5,   /* field[5] = commitment_fee */
-  2,   /* field[2] = locktime_blocks */
+  5,   /* field[5] = anchor */
+  4,   /* field[4] = commitment_fee */
   1,   /* field[1] = locktime_seconds */
-  3,   /* field[3] = revocation_hash */
-  4,   /* field[4] = script_to_me */
+  2,   /* field[2] = revocation_hash */
+  3,   /* field[3] = script_to_me */
   0,   /* field[0] = seed */
-  7,   /* field[7] = tx_version */
+  6,   /* field[6] = tx_version */
 };
-static const ProtobufCIntRange open_channel__number_ranges[1 + 1] =
+static const ProtobufCIntRange open_channel__number_ranges[2 + 1] =
 {
   { 1, 0 },
-  { 0, 8 }
+  { 4, 2 },
+  { 0, 7 }
 };
 const ProtobufCMessageDescriptor open_channel__descriptor =
 {
@@ -1505,10 +1493,10 @@ const ProtobufCMessageDescriptor open_channel__descriptor =
   "OpenChannel",
   "",
   sizeof(OpenChannel),
-  8,
+  7,
   open_channel__field_descriptors,
   open_channel__field_indices_by_name,
-  1,  open_channel__number_ranges,
+  2,  open_channel__number_ranges,
   (ProtobufCMessageInit) open_channel__init,
   NULL,NULL,NULL    /* reserved[123] */
 };
diff --git a/lightning.pb-c.h b/lightning.pb-c.h
index b90b8bd92..376017545 100644
--- a/lightning.pb-c.h
+++ b/lightning.pb-c.h
@@ -169,12 +169,6 @@ struct  _Anchor
     , 0,NULL, NULL, NULL, 0, 0, 0 }
 
 
-typedef enum {
-  OPEN_CHANNEL__LOCKTIME__NOT_SET = 0,
-  OPEN_CHANNEL__LOCKTIME_LOCKTIME_SECONDS = 2,
-  OPEN_CHANNEL__LOCKTIME_LOCKTIME_BLOCKS = 3,
-} OpenChannel__LocktimeCase;
-
 /*
  * Set channel params.
  */
@@ -185,6 +179,10 @@ struct  _OpenChannel
    * Seed which sets order we create outputs for all transactions.
    */
   uint64_t seed;
+  /*
+   * Relative locktime for outputs going to us.
+   */
+  uint32_t locktime_seconds;
   /*
    * Hash seed for revoking commitment transactions.
    */
@@ -205,15 +203,10 @@ struct  _OpenChannel
    * Maximum transaction version we support.
    */
   uint32_t tx_version;
-  OpenChannel__LocktimeCase locktime_case;
-  union {
-    uint32_t locktime_seconds;
-    uint32_t locktime_blocks;
-  };
 };
 #define OPEN_CHANNEL__INIT \
  { PROTOBUF_C_MESSAGE_INIT (&open_channel__descriptor) \
-    , 0, NULL, {0,NULL}, 0, NULL, 0, OPEN_CHANNEL__LOCKTIME__NOT_SET, {} }
+    , 0, 0, NULL, {0,NULL}, 0, NULL, 0 }
 
 
 /*
diff --git a/lightning.proto b/lightning.proto
index 6b1c77102..c9a7851db 100644
--- a/lightning.proto
+++ b/lightning.proto
@@ -67,10 +67,7 @@ message open_channel {
   // Seed which sets order we create outputs for all transactions.
   required uint64 seed = 1;
   // Relative locktime for outputs going to us.
-  oneof locktime {
-    uint32 locktime_seconds = 2;
-    uint32 locktime_blocks = 3;
-  }
+  required uint32 locktime_seconds = 2;
   // Hash seed for revoking commitment transactions.
   required sha256_hash revocation_hash = 4;
   // How to pay money to us from commit_tx.
diff --git a/pkt.c b/pkt.c
index 121018e76..278cfb907 100644
--- a/pkt.c
+++ b/pkt.c
@@ -78,7 +78,6 @@ struct pkt *openchannel_pkt(const tal_t *ctx,
 	o.script_to_me.data = (void *)script;
 	o.commitment_fee = commitment_fee;
 	o.anchor = anchor;
-	o.locktime_case = OPEN_CHANNEL__LOCKTIME_LOCKTIME_SECONDS;
 	o.locktime_seconds = rel_locktime_seconds;
 	o.tx_version = BITCOIN_TX_VERSION;