diff --git a/msg_helpers.go b/msg_helpers.go
index cbcab57b..6fb64475 100644
--- a/msg_helpers.go
+++ b/msg_helpers.go
@@ -683,6 +683,13 @@ func packDataAplPrefix(p *APLPrefix, msg []byte, off int) (int, error) {
 	if p.Negation {
 		n = 0x80
 	}
+
+	// trim trailing zero bytes as specified in RFC3123 Sections 4.1 and 4.2.
+	i := len(addr) - 1
+	for ; i >= 0 && addr[i] == 0; i-- {
+	}
+	addr = addr[:i+1]
+
 	adflen := uint8(len(addr)) & 0x7f
 	off, err = packUint8(n|adflen, msg, off)
 	if err != nil {
diff --git a/msg_helpers_test.go b/msg_helpers_test.go
index 70e3b238..c1fa195a 100644
--- a/msg_helpers_test.go
+++ b/msg_helpers_test.go
@@ -180,6 +180,20 @@ func TestPackDataAplPrefix(t *testing.T) {
 			net.CIDRMask(48, 128),
 			[]byte{0x00, 0x02, 0x30, 0x06, 0x20, 0x01, 0x0d, 0xb8, 0xca, 0xfe},
 		},
+		{
+			"with trailing zero bytes 2:2001:db8:cafe::0/64",
+			false,
+			net.ParseIP("2001:db8:cafe::"),
+			net.CIDRMask(64, 128),
+			[]byte{0x00, 0x02, 0x40, 0x06, 0x20, 0x01, 0x0d, 0xb8, 0xca, 0xfe},
+		},
+		{
+			"no non-zero bytes 2::/16",
+			false,
+			net.ParseIP("::"),
+			net.CIDRMask(16, 128),
+			[]byte{0x00, 0x02, 0x10, 0x00},
+		},
 		{
 			"!2:2001:db8::/32",
 			true,
@@ -209,6 +223,11 @@ func TestPackDataAplPrefix(t *testing.T) {
 			if !bytes.Equal(tt.expect, out[:off]) {
 				t.Fatalf("expected output %02x, got %02x", tt.expect, out[:off])
 			}
+			// Make sure the packed bytes would be accepted by its own unpack
+			_, _, err = unpackDataAplPrefix(out, 0)
+			if err != nil {
+				t.Fatalf("expected no error, got %q", err)
+			}
 		})
 	}
 }