diff --git a/cmd/stayrtr/stayrtr.go b/cmd/stayrtr/stayrtr.go
index 93a8967..a934f67 100644
--- a/cmd/stayrtr/stayrtr.go
+++ b/cmd/stayrtr/stayrtr.go
@@ -180,24 +180,29 @@ func decodeJSON(data []byte) (*prefixfile.VRPList, error) {
 	return &vrplistjson, err
 }
 
-func checkPrefixLengths(prefix *net.IPNet, maxLength uint8) bool {
+func isValidPrefixLength(prefix *net.IPNet, maxLength uint8) bool {
 	plen, max := net.IPMask.Size(prefix.Mask)
 
-	if uint8(plen) > maxLength || maxLength > uint8(max) {
+	if plen == 0 || uint8(plen) > maxLength || maxLength > uint8(max) {
 		log.Errorf("%s Maxlength wrong: %d - %d", prefix, plen, maxLength)
 		return false
 	}
 	return true
 }
 
+// processData will take a slice of prefix.VRPJson and attempt to convert them to a slice of rtr.VRP.
+// Will check the following:
+// 1 - The prefix is a valid prefix
+// 2 - The ASN is a valid ASN
+// 3 - The MaxLength is valid
+// Will return a deduped slice, as well as total VRPs, IPv4 VRPs, and IPv6 VRPs
 func processData(vrplistjson []prefixfile.VRPJson) ([]rtr.VRP, int, int, int) {
 	filterDuplicates := make(map[string]bool)
 
-	vrplist := make([]rtr.VRP, 0)
-
-	var count int
+	var vrplist []rtr.VRP
 	var countv4 int
 	var countv6 int
+
 	for _, v := range vrplistjson {
 		prefix, err := v.GetPrefix2()
 		if err != nil {
@@ -210,24 +215,22 @@ func processData(vrplistjson []prefixfile.VRPJson) ([]rtr.VRP, int, int, int) {
 			continue
 		}
 
-		if !checkPrefixLengths(prefix, v.Length) {
+		if !isValidPrefixLength(prefix, v.Length) {
 			continue
 		}
 
 		if prefix.IP.To4() != nil {
 			countv4++
-		} else if prefix.IP.To16() != nil {
+		} else {
 			countv6++
 		}
-		count++
 
 		key := fmt.Sprintf("%s,%d,%d", prefix, asn, v.Length)
 		_, exists := filterDuplicates[key]
-		if !exists {
-			filterDuplicates[key] = true
-		} else {
+		if exists {
 			continue
 		}
+		filterDuplicates[key] = true
 
 		vrp := rtr.VRP{
 			Prefix: *prefix,
@@ -236,7 +239,7 @@ func processData(vrplistjson []prefixfile.VRPJson) ([]rtr.VRP, int, int, int) {
 		}
 		vrplist = append(vrplist, vrp)
 	}
-	return vrplist, count, countv4, countv6
+	return vrplist, countv4 + countv6, countv4, countv6
 }
 
 type IdenticalFile struct {
@@ -272,8 +275,7 @@ func (s *state) updateFromNewState() error {
 
 	vrps, count, countv4, countv6 := processData(vrpsjson)
 
-	log.Infof("New update (%v uniques, %v total prefixes).",
-		len(vrps), count)
+	log.Infof("New update (%v uniques, %v total prefixes).", len(vrps), count)
 
 	s.server.AddVRPs(vrps)
 
diff --git a/cmd/stayrtr/stayrtr_test.go b/cmd/stayrtr/stayrtr_test.go
new file mode 100644
index 0000000..5865a6b
--- /dev/null
+++ b/cmd/stayrtr/stayrtr_test.go
@@ -0,0 +1,124 @@
+package main
+
+import (
+	"net"
+	"testing"
+
+	rtr "github.com/bgp/stayrtr/lib"
+	"github.com/bgp/stayrtr/prefixfile"
+	"github.com/google/go-cmp/cmp"
+)
+
+func TestProcessData(t *testing.T) {
+	var stuff []prefixfile.VRPJson
+	stuff = append(stuff,
+		prefixfile.VRPJson{
+			Prefix: "192.168.0.0/24",
+			Length: 24,
+			ASN:    123,
+			TA:     "testrir",
+		},
+		prefixfile.VRPJson{
+			Prefix: "192.168.0.0/24",
+			Length: 24,
+			TA:     "testrir",
+		},
+		prefixfile.VRPJson{
+			Prefix: "2001:db8::/32",
+			Length: 33,
+			ASN:    "AS123",
+			TA:     "testrir",
+		},
+		prefixfile.VRPJson{
+			Prefix: "192.168.1.0/24",
+			Length: 25,
+			ASN:    123,
+			TA:     "testrir",
+		},
+		// Invalid. Length is 0
+		prefixfile.VRPJson{
+			Prefix: "192.168.1.0/24",
+			Length: 0,
+			ASN:    123,
+			TA:     "testrir",
+		},
+		// Invalid. Length less than prefix length
+		prefixfile.VRPJson{
+			Prefix: "192.168.1.0/24",
+			Length: 16,
+			ASN:    123,
+			TA:     "testrir",
+		},
+		// Invalid. 129 is invalid for IPv6
+		prefixfile.VRPJson{
+			Prefix: "2001:db8::/32",
+			Length: 129,
+			ASN:    123,
+			TA:     "testrir",
+		},
+		// Invalid. 33 is invalid for IPv4
+		prefixfile.VRPJson{
+			Prefix: "192.168.1.0/24",
+			Length: 33,
+			ASN:    123,
+			TA:     "testrir",
+		},
+		// Invalid. Not a prefix
+		prefixfile.VRPJson{
+			Prefix: "192.168.1.0",
+			Length: 24,
+			ASN:    123,
+			TA:     "testrir",
+		},
+		// Invalid. Not a prefix
+		prefixfile.VRPJson{
+			Prefix: "👻",
+			Length: 24,
+			ASN:    123,
+			TA:     "testrir",
+		},
+		// Invalid. Invalid ASN string
+		prefixfile.VRPJson{
+			Prefix: "192.168.1.0/22",
+			Length: 22,
+			ASN:    "ASN123",
+			TA:     "testrir",
+		},
+	)
+	got, count, v4count, v6count := processData(stuff)
+	want := []rtr.VRP{
+		{
+			Prefix: MustParseIPNet("192.168.0.0/24"),
+			MaxLen: 24,
+			ASN:    123,
+		},
+		{
+			Prefix: MustParseIPNet("2001:db8::/32"),
+			MaxLen: 33,
+			ASN:    123,
+		},
+		{
+			Prefix: MustParseIPNet("192.168.1.0/24"),
+			MaxLen: 25,
+			ASN:    123,
+		},
+	}
+	if count != 3 || v4count != 2 || v6count != 1 {
+		t.Errorf("Wanted count = 3, v4count = 2, v6count = 1, but got %d, %d, %d", count, v4count, v6count)
+	}
+
+	if !cmp.Equal(got, want) {
+		t.Errorf("Want (%+v), Got (%+v)", want, got)
+	}
+}
+
+// MustParseIPNet is a test helper function to return a net.IPNet
+// This should only be called in test code, and it'll panic on test set up
+// if unable to parse.
+func MustParseIPNet(prefix string) net.IPNet {
+	_, ipnet, err := net.ParseCIDR(prefix)
+	if err != nil {
+		panic(err)
+	}
+	return *ipnet
+}
diff --git a/prefixfile/slurm.go b/prefixfile/slurm.go
index 168526f..03036b2 100644
--- a/prefixfile/slurm.go
+++ b/prefixfile/slurm.go
@@ -1,3 +1,5 @@
+// rfc8416
+
 package prefixfile
 
 import (