diff --git a/README.md b/README.md
index 14383e63f1f5..f07fe838c2c7 100644
--- a/README.md
+++ b/README.md
@@ -4,6 +4,8 @@ MsQuic
 MsQuic is an implementation of the [IETF QUIC](https://tools.ietf.org/html/draft-ietf-quic-transport)
 protocol by Microsoft. It is a cross platform, general purpose QUIC library written in C.
 
+[![Build Status](https://microsoft.visualstudio.com/OS/_apis/build/status/microsoft.msquic?branchName=master)](https://microsoft.visualstudio.com/OS/_build/latest?definitionId=45975&branchName=master)
+
 ## Protocol Features
 
 QUIC has many benefits when compared to existing TLS over TCP scenarios:
diff --git a/core/packet_builder.c b/core/packet_builder.c
index 9cd1970daf5a..265ae9eaecb9 100644
--- a/core/packet_builder.c
+++ b/core/packet_builder.c
@@ -142,6 +142,7 @@ QuicPacketBuilderPrepare(
         DatagramSize = (uint16_t)Connection->Send.Allowance;
     }
     QUIC_DBG_ASSERT(!IsPathMtuDiscovery || !IsTailLossProbe); // Never both.
+    QUIC_DBG_ASSERT(NewPacketKey != NULL);
 
     //
     // Next, make sure the current QUIC packet matches the new packet type. If
@@ -513,6 +514,8 @@ QuicPacketBuilderFinalizeHeaderProtection(
     _Inout_ QUIC_PACKET_BUILDER* Builder
     )
 {
+    QUIC_DBG_ASSERT(Builder->Key != NULL);
+
     QUIC_STATUS Status;
     if (QUIC_FAILED(
         Status =
@@ -589,6 +592,7 @@ QuicPacketBuilderFinalize(
     QUIC_DBG_ASSERT(Builder->Datagram->Length >= Builder->MinimumDatagramLength);
     QUIC_DBG_ASSERT(Builder->Datagram->Length >= (uint32_t)(Builder->DatagramLength + Builder->EncryptionOverhead));
     QUIC_DBG_ASSERT(Builder->Metadata->FrameCount != 0);
+    QUIC_DBG_ASSERT(Builder->Key != NULL);
 
     uint8_t* Header =
         (uint8_t*)Builder->Datagram->Buffer + Builder->PacketStart;
@@ -774,6 +778,7 @@ QuicPacketBuilderFinalize(
             //
             // Update the packet key in use by the send builder.
             //
+            QUIC_DBG_ASSERT(Connection->Crypto.TlsState.WriteKeys[QUIC_PACKET_KEY_1_RTT] != NULL);
             Builder->Key = Connection->Crypto.TlsState.WriteKeys[QUIC_PACKET_KEY_1_RTT];
         }
     }
diff --git a/core/send.c b/core/send.c
index 4e778d70b8ea..6949f390408c 100644
--- a/core/send.c
+++ b/core/send.c
@@ -449,7 +449,16 @@ QuicSendWriteFrames(
     }
 
     if (Send->SendFlags & (QUIC_CONN_SEND_FLAG_CONNECTION_CLOSE | QUIC_CONN_SEND_FLAG_APPLICATION_CLOSE)) {
-        BOOLEAN IsApplicationClose = !!(Send->SendFlags & QUIC_CONN_SEND_FLAG_APPLICATION_CLOSE);
+        BOOLEAN IsApplicationClose =
+            !!(Send->SendFlags & QUIC_CONN_SEND_FLAG_APPLICATION_CLOSE);
+        if (Connection->State.ClosedRemotely) {
+            //
+            // Application closed should only be the origination of the
+            // connection close. If we're closed remotely already, we should
+            // just acknowledge the close with a connection close frame.
+            //
+            IsApplicationClose = FALSE;
+        }
 
         QUIC_CONNECTION_CLOSE_EX Frame = {
             IsApplicationClose,
@@ -459,23 +468,6 @@ QuicSendWriteFrames(
             Connection->CloseReasonPhrase
         };
 
-        if (Connection->State.ClosedRemotely) {
-            //
-            // If we are already closed remotely, then that means we are just
-            // responding to (acknowledging in a sense) a received close frame.
-            // In that case, we just send an error code value of 0. Otherwise,
-            // we send whatever error code we have cached.
-            //
-            Frame.ErrorCode = 0;
-            //
-            // Application closed should always be the origination of the
-            // connection close. In other words, if the peer closed the
-            // connection first, then we should be responding with a connection
-            // close frame, instead of an app close frame.
-            //
-            QUIC_DBG_ASSERT(!IsApplicationClose);
-        }
-
         if (QuicConnCloseFrameEncode(
                 &Frame,
                 &Builder->DatagramLength,