diff --git a/generate/generate.go b/generate/generate.go
index ea2762b..1792b40 100644
--- a/generate/generate.go
+++ b/generate/generate.go
@@ -11,6 +11,7 @@ import "git.tebibyte.media/sashakoshka/hopp/tape"
 
 const imports =
 `
+import "fmt"
 import "git.tebibyte.media/sashakoshka/hopp"
 import "git.tebibyte.media/sashakoshka/hopp/tape"
 `
@@ -41,7 +42,9 @@ func Send(trans hopp.Trans, message Message) (n int, err error) {
 	if err != nil { return n, err }
 	defer writer.Close()
 	encoder := tape.NewEncoder(writer)
-	return message.Encode(encoder)
+	n, err = message.Encode(encoder)
+	if err != nil { return n, err }
+	return n, encoder.Flush()
 }
 
 // canAssign determines if data from the given source tag can be assigned to
@@ -1216,7 +1219,7 @@ func (this *Generator) generateReceive() (n int, err error) {
 		nn, err = this.iprintf("switch method {\n")
 		n += nn; if err != nil { return n, err }
 		for method, message := range this.protocol.Messages {
-			nn, err = this.iprintf("case %04X:\n", method)
+			nn, err = this.iprintf("case 0x%04X:\n", method)
 			n += nn; if err != nil { return n, err }
 			this.push()
 				nn, err = this.iprintf(
@@ -1234,7 +1237,7 @@ func (this *Generator) generateReceive() (n int, err error) {
 		}
 		nn, err = this.iprint("}\n")
 		n += nn; if err != nil { return n, err }
-		nn, err = this.iprintf("return nil, n, hopp.ErrUnknownMethod\n")
+		nn, err = this.iprint("return nil, n, fmt.Errorf(\"%w: M%04X\", hopp.ErrUnknownMethod, method)\n")
 		n += nn; if err != nil { return n, err }
 	this.pop()
 	nn, err = this.iprint("}\n")