diff --git a/frames/ack_frame_new.go b/frames/ack_frame_new.go
index 918b1a3d0..171defe1f 100644
--- a/frames/ack_frame_new.go
+++ b/frames/ack_frame_new.go
@@ -9,8 +9,12 @@ import (
 	"github.com/lucas-clemente/quic-go/utils"
 )
 
-// ErrInvalidAckRanges occurs when a client sends inconsistent ACK ranges
-var ErrInvalidAckRanges = errors.New("AckFrame: ACK frame contains invalid ACK ranges")
+var (
+	// ErrInvalidAckRanges occurs when a client sends inconsistent ACK ranges
+	ErrInvalidAckRanges = errors.New("AckFrame: ACK frame contains invalid ACK ranges")
+	// ErrInvalidFirstAckRange occurs when the first ACK range contains no packets
+	ErrInvalidFirstAckRange = errors.New("AckFrame: ACK frame has invalid first ACK range")
+)
 
 var (
 	errInconsistentAckLargestAcked = errors.New("internal inconsistency: LargestAcked does not match ACK ranges")
@@ -75,6 +79,9 @@ func ParseAckFrameNew(r *bytes.Reader, version protocol.VersionNumber) (*AckFram
 	if err != nil {
 		return nil, err
 	}
+	if ackBlockLength < 1 {
+		return nil, ErrInvalidFirstAckRange
+	}
 
 	if ackBlockLength > largestAcked {
 		return nil, ErrInvalidAckRanges
diff --git a/frames/ack_frame_new_test.go b/frames/ack_frame_new_test.go
index b4dbfa61b..8f5f544f2 100644
--- a/frames/ack_frame_new_test.go
+++ b/frames/ack_frame_new_test.go
@@ -30,10 +30,21 @@ var _ = Describe("AckFrame", func() {
 		})
 
 		It("parses a frame with a 48 bit packet number", func() {
-			b := bytes.NewReader([]byte{0x4c, 0x37, 0x13, 0xad, 0xfb, 0xca, 0xde, 0x0, 0x0, 0x0, 0x1, 0, 0, 0, 0, 0})
-			frame, err := ParseAckFrameNew(b, protocol.Version34)
+			b := bytes.NewReader([]byte{0x4c, 0x37, 0x13, 0xad, 0xfb, 0xca, 0xde, 0x0, 0x0, 0x5, 0x1, 0, 0, 0, 0, 0})
+			frame, err := ParseAckFrameNew(b, 0)
 			Expect(err).ToNot(HaveOccurred())
 			Expect(frame.LargestAcked).To(Equal(protocol.PacketNumber(0xdecafbad1337)))
+			Expect(frame.LowestAcked).To(Equal(protocol.PacketNumber(0xdecafbad1337 - 5 + 1)))
+			Expect(frame.HasMissingRanges()).To(BeFalse())
+			Expect(b.Len()).To(BeZero())
+		})
+
+		It("parses a frame with 1 ACKed packet", func() {
+			b := bytes.NewReader([]byte{0x40, 0x10, 0x8e, 0x0, 0x1, 0x0})
+			frame, err := ParseAckFrameNew(b, 0)
+			Expect(err).ToNot(HaveOccurred())
+			Expect(frame.LargestAcked).To(Equal(protocol.PacketNumber(0x10)))
+			Expect(frame.LowestAcked).To(Equal(protocol.PacketNumber(0x10)))
 			Expect(frame.HasMissingRanges()).To(BeFalse())
 			Expect(b.Len()).To(BeZero())
 		})
@@ -62,6 +73,12 @@ var _ = Describe("AckFrame", func() {
 			Expect(err).To(MatchError(ErrInvalidAckRanges))
 		})
 
+		It("errors when the first ACK range is empty", func() {
+			b := bytes.NewReader([]byte{0x40, 0x9, 0x8e, 0x0, 0x0, 0x1, 0})
+			_, err := ParseAckFrameNew(b, 0)
+			Expect(err).To(MatchError(ErrInvalidFirstAckRange))
+		})
+
 		Context("ACK blocks", func() {
 			It("parses a frame with one ACK block", func() {
 				b := bytes.NewReader([]byte{0x60, 0x18, 0x94, 0x1, 0x1, 0x3, 0x2, 0x10, 0x2, 0x1, 0x5c, 0xd5, 0x0, 0x0, 0x0, 0x95, 0x0})