diff --git a/.gitignore b/.gitignore
index fdcd5db..003a9b7 100644
--- a/.gitignore
+++ b/.gitignore
@@ -29,3 +29,6 @@ main
 .swp
 main
 super-graph
+*-fuzz.zip
+crashers
+suppressions
\ No newline at end of file
diff --git a/go.mod b/go.mod
index 2188d09..d90b66b 100644
--- a/go.mod
+++ b/go.mod
@@ -12,6 +12,7 @@ require (
 	github.com/dgrijalva/jwt-go v3.2.0+incompatible
 	github.com/dlclark/regexp2 v1.2.0 // indirect
 	github.com/dop251/goja v0.0.0-20190912223329-aa89e6a4c733
+	github.com/dvyukov/go-fuzz v0.0.0-20191022152526-8cb203812681 // indirect
 	github.com/fsnotify/fsnotify v1.4.7
 	github.com/garyburd/redigo v1.6.0
 	github.com/go-sourcemap/sourcemap v2.1.2+incompatible // indirect
diff --git a/go.sum b/go.sum
index bdda6e9..848e404 100644
--- a/go.sum
+++ b/go.sum
@@ -57,6 +57,8 @@ github.com/dlclark/regexp2 v1.2.0 h1:8sAhBGEM0dRWogWqWyQeIJnxjWO6oIjl8FKqREDsGfk
 github.com/dlclark/regexp2 v1.2.0/go.mod h1:2pZnwuY/m+8K6iRw6wQdMtk+rH5tNGR1i55kozfMjCc=
 github.com/dop251/goja v0.0.0-20190912223329-aa89e6a4c733 h1:cyNc40Dx5YNEO94idePU8rhVd3dn+sd04Arh0kDBAaw=
 github.com/dop251/goja v0.0.0-20190912223329-aa89e6a4c733/go.mod h1:Mw6PkjjMXWbTj+nnj4s3QPXq1jaT0s5pC0iFD4+BOAA=
+github.com/dvyukov/go-fuzz v0.0.0-20191022152526-8cb203812681 h1:3WV5aRRj1ELP3RcLlBp/v0WJTuy47OQMkL9GIQq8QEE=
+github.com/dvyukov/go-fuzz v0.0.0-20191022152526-8cb203812681/go.mod h1:11Gm+ccJnvAhCNLlf5+cS9KjtbaD5I5zaZpFMsTHWTw=
 github.com/fsnotify/fsnotify v1.4.7 h1:IXs+QLmnXW2CcXuY+8Mzv/fWEsPGWxqefPtCP5CnV9I=
 github.com/fsnotify/fsnotify v1.4.7/go.mod h1:jwhsz4b93w/PPRr/qN1Yymfu8t87LnFCMoQvtojpjFo=
 github.com/garyburd/redigo v1.6.0 h1:0VruCpn7yAIIu7pWVClQC8wxCJEcG3nyzpMSHKi1PQc=
diff --git a/jsn/filter.go b/jsn/filter.go
index c55097a..04f0cce 100644
--- a/jsn/filter.go
+++ b/jsn/filter.go
@@ -97,8 +97,7 @@ func Filter(w *bytes.Buffer, b []byte, keys []string) error {
 		case state == expectNumClose &&
 			((b[i] < '0' || b[i] > '9') &&
 				(b[i] != '.' && b[i] != 'e' && b[i] != 'E' && b[i] != '+' && b[i] != '-')):
-			i--
-			e = i
+			e = i - 1
 
 		case state == expectValue &&
 			(b[i] == 'f' || b[i] == 'F' || b[i] == 't' || b[i] == 'T'):
diff --git a/jsn/fuzz.go b/jsn/fuzz.go
index 6a0b21f..b48fb6b 100644
--- a/jsn/fuzz.go
+++ b/jsn/fuzz.go
@@ -3,7 +3,7 @@ package jsn
 import "bytes"
 
 // FuzzerEntrypoint for Fuzzbuzz
-func FuzzerEntryPoint(data []byte) int {
+func Fuzz(data []byte) int {
 	err1 := Validate(string(data))
 
 	var b1 bytes.Buffer
@@ -28,8 +28,8 @@ func FuzzerEntryPoint(data []byte) int {
 	Keys(data)
 
 	if err1 != nil || err2 != nil || err3 != nil {
-		return -1
+		return 0
 	}
 
-	return 0
+	return 1
 }
diff --git a/jsn/fuzz_test.go b/jsn/fuzz_test.go
new file mode 100644
index 0000000..2b66964
--- /dev/null
+++ b/jsn/fuzz_test.go
@@ -0,0 +1,59 @@
+package jsn
+
+import "testing"
+
+func TestFuzzCrashers(t *testing.T) {
+
+	var crashers = []string{
+		"00\"0000\"0{",
+		"6\",\n\t\t\t\"something\": " +
+			"null\n\t\t},\n\t\t{\n\t\t\t\"id" +
+			"\": 12,\n\t\t\t\"full_name" +
+			"\": \"Brenton Bauch Ph" +
+			"D\",\n\t\t\t\"email\": \"ren" +
+			"ee@miller.co\",\n\t\t\t\"_" +
+			"_twitter_id\": 1\n\t\t}," +
+			"\n\t\t{\n\t\t\t\"id\": 13,\n\t\t" +
+			"\t\"full_name\": \"Daine" +
+			" Gleichner\",\n\t\t\t\"ema" +
+			"il\": \"andrea@gmail.c" +
+			"om\",\n\t\t\t\"__twitter_i" +
+			"d\": \"\",\n\t\t\t\"id__twit" +
+			"ter_id\": \"NOOO\",\n\t\t\t" +
+			"\"work_email\": \"andre" +
+			"a@nienow.co\"\n\t\t}\n\t]}" +
+			"\n\t}",
+		"0000\"0000\"0{",
+		"0000\"\"{",
+		"0000\"000\"{",
+		"0\"\"{",
+		"\"0\"{",
+		"000\"0\"{",
+		"0\"0000\"0{",
+		"000\"\"{",
+		"0\"00\"{",
+		"000\"0000\"0{",
+		"000\"00\"{",
+		"\"\"{",
+		"0\"0000\"{",
+		"\"000\"00{",
+		"0000\"00\"{",
+		"00\"0\"{",
+		"0\"0\"{",
+		"000\"0000\"{",
+		"00\"0000\"{",
+		"0000\"0000\"{",
+		"\"000\"{",
+		"00\"00\"{",
+		"00\"0000\"00{",
+		"0\"0000\"00{",
+		"00\"\"{",
+		"0000\"0\"{",
+		"000\"000\"{",
+		"\"00000000\"{",
+	}
+
+	for _, f := range crashers {
+		Fuzz([]byte(f))
+	}
+}
diff --git a/jsn/get.go b/jsn/get.go
index 29c37ac..86ba3b5 100644
--- a/jsn/get.go
+++ b/jsn/get.go
@@ -105,8 +105,7 @@ func Get(b []byte, keys [][]byte) []Field {
 		case state == expectNumClose &&
 			((b[i] < '0' || b[i] > '9') &&
 				(b[i] != '.' && b[i] != 'e' && b[i] != 'E' && b[i] != '+' && b[i] != '-')):
-			i--
-			e = i
+			e = i - 1
 
 		case state == expectValue &&
 			(b[i] == 'f' || b[i] == 'F' || b[i] == 't' || b[i] == 'T'):
diff --git a/jsn/keys.go b/jsn/keys.go
index e1c0e1b..0ebf69f 100644
--- a/jsn/keys.go
+++ b/jsn/keys.go
@@ -12,6 +12,7 @@ func Keys(b []byte) [][]byte {
 	ae := 0
 
 	for i := 0; i < len(b); i++ {
+
 		if state == expectObjClose || state == expectListClose {
 			switch b[i] {
 			case '{', '[':
@@ -88,8 +89,7 @@ func Keys(b []byte) [][]byte {
 		case state == expectNumClose &&
 			((b[i] < '0' || b[i] > '9') &&
 				(b[i] != '.' && b[i] != 'e' && b[i] != 'E' && b[i] != '+' && b[i] != '-')):
-			i--
-			e = i
+			e = i - 1
 
 		case state == expectValue &&
 			(b[i] == 'f' || b[i] == 'F' || b[i] == 't' || b[i] == 'T'):
diff --git a/jsn/replace.go b/jsn/replace.go
index 43389a5..0f5b67b 100644
--- a/jsn/replace.go
+++ b/jsn/replace.go
@@ -86,8 +86,7 @@ func Replace(w *bytes.Buffer, b []byte, from, to []Field) error {
 		case state == expectNumClose &&
 			((b[i] < '0' || b[i] > '9') &&
 				(b[i] != '.' && b[i] != 'e' && b[i] != 'E' && b[i] != '+' && b[i] != '-')):
-			i--
-			e = i
+			e = i - 1
 
 		case state == expectValue &&
 			(b[i] == 'f' || b[i] == 'F' || b[i] == 't' || b[i] == 'T'):
@@ -156,7 +155,7 @@ func Replace(w *bytes.Buffer, b []byte, from, to []Field) error {
 
 	if ws == -1 || (ws == 0 && we == len(b)) {
 		w.Write(b)
-	} else {
+	} else if ws < we {
 		w.Write(b[ws:we])
 	}
 
diff --git a/jsn/strip.go b/jsn/strip.go
index 3b66fd0..e6dc64e 100644
--- a/jsn/strip.go
+++ b/jsn/strip.go
@@ -70,8 +70,7 @@ func Strip(b []byte, path [][]byte) []byte {
 		case state == expectNumClose &&
 			((b[i] < '0' || b[i] > '9') &&
 				(b[i] != '.' && b[i] != 'e' && b[i] != 'E' && b[i] != '+' && b[i] != '-')):
-			i--
-			e = i
+			e = i - 1
 
 		case state == expectValue &&
 			(b[i] == 'f' || b[i] == 'F' || b[i] == 't' || b[i] == 'T'):
diff --git a/qcode/corpus/001.gql b/qcode/corpus/001.gql
new file mode 100644
index 0000000..ae381f8
--- /dev/null
+++ b/qcode/corpus/001.gql
@@ -0,0 +1,21 @@
+query {
+  products(
+    # returns only 30 items
+    limit: 30,
+
+    # starts from item 10, commented out for now
+    # offset: 10,
+
+    # orders the response items by highest price
+    order_by: { price: desc },
+
+    # no duplicate prices returned
+    distinct: [ price ]
+    
+    # only items with an id >= 30 and < 30 are returned
+    where: { id: { and: { greater_or_equals: 20, lt: 28 } } }) {
+    id
+    name
+    price
+  }
+}
\ No newline at end of file
diff --git a/qcode/corpus/002.gql b/qcode/corpus/002.gql
new file mode 100644
index 0000000..d0aa529
--- /dev/null
+++ b/qcode/corpus/002.gql
@@ -0,0 +1,14 @@
+query {
+  products(
+    where: { 
+      or: { 
+        not: { id: { is_null: true } }, 
+        price: { gt: 10 },
+        price: { lt: 20 } 
+      } }
+    ) {
+    id
+    name
+    price
+  }
+}
\ No newline at end of file
diff --git a/qcode/corpus/003.gql b/qcode/corpus/003.gql
new file mode 100644
index 0000000..a57440b
--- /dev/null
+++ b/qcode/corpus/003.gql
@@ -0,0 +1,12 @@
+query {
+  products(
+    where: { 
+      and: { 
+        not: { id: { is_null: true } }, 
+        price: { gt: 10 } 
+      }}) {
+    id
+    name
+    price
+  }
+}
\ No newline at end of file
diff --git a/qcode/fuzz.go b/qcode/fuzz.go
index 89a4a3c..25a8ca5 100644
--- a/qcode/fuzz.go
+++ b/qcode/fuzz.go
@@ -1,14 +1,12 @@
 package qcode
 
 // FuzzerEntrypoint for Fuzzbuzz
-func FuzzerEntrypoint(data []byte) int {
-	//testData := string(data)
-
+func Fuzz(data []byte) int {
 	qcompile, _ := NewCompiler(Config{})
 	_, err := qcompile.Compile(data, "user")
 	if err != nil {
-		return -1
+		return 0
 	}
 
-	return 0
+	return 1
 }