commit - 6e66f3c0b53654afdd46a2b79cbb0b3eee57d57c
commit + 63c84aa90a323a2d425c79f41e1f6c3cbdd15547
blob - 5e305f87cbefdf120171822a73dd51b8fd2e13ac
blob + 09a3633d1aeadda61c049a24a985c1230e145a93
--- server.go
+++ server.go
@@ -32,7 +32,7 @@ func ServeConn(ctx context.Context, cn net.Conn, handl
 
 	if err := servernegotiate(negctx, ch, DefaultVersion); err != nil {
 		// TODO(stevvooe): Need better error handling and retry support here.
-		return fmt.Errorf("error negotiating version:", err)
+		return fmt.Errorf("error negotiating version: %s", err)
 	}
 
 	ctx = withVersion(ctx, DefaultVersion)
blob - ac20fb9dfd45e42713513aee43a5ad975d41c0cc
blob + ee72e88d1e2a28e9e88d02d690de78d79ef3d246
--- version.go
+++ version.go
@@ -80,9 +80,15 @@ func servernegotiate(ctx context.Context, ch Channel, 
 	if mv.Version != version {
 		// TODO(stevvooe): Not the best place to do version handling. We need
 		// to have a way to pass supported versions into this method then have
-		// it return the actual version. For now, respond with unknown for
+		// it return the actual version. For now, respond with 9P2000 for
 		// anything that doesn't match the provided version string.
-		respmsg.Version = "unknown"
+		//
+		// version(9) says "The server may respond with the client’s
+		// version string, or a version string identifying an earlier
+		// defined protocol version. Currently, the only defined
+		// version is the 6 characters 9P2000." Therefore, it is always
+		// OK to respond with this.
+		respmsg.Version = "9P2000"
 	}
 
 	if int(mv.MSize) < ch.MSize() {