diff --git a/src/expressions.ts b/src/expressions.ts
index 5b40397..e36dad3 100644
--- a/src/expressions.ts
+++ b/src/expressions.ts
@@ -62,7 +62,7 @@ export function boolCommonExpr(value: SourceArray, index: number): Lexer.Token {
   }
 
   let commonMoreExpr = undefined;
-  if (token.type === Lexer.TokenType.CommonExpression) {
+  if (token. type === Lexer.TokenType.CommonExpression) {
     commonMoreExpr =
       eqExpr(value, token.next) ||
       neExpr(value, token.next) ||
diff --git a/src/lexer.ts b/src/lexer.ts
index 52924ba..3cb32bb 100644
--- a/src/lexer.ts
+++ b/src/lexer.ts
@@ -430,6 +430,7 @@ export function pchar(value: SourceArray, index: number): number {
     index
   );
 }
+
 export function pcharNoSQUOTE(value: SourceArray, index: number): number {
   if (
     unreserved(value[index]) ||
@@ -438,11 +439,13 @@ export function pcharNoSQUOTE(value: SourceArray, index: number): number {
   ) {
     return index + 1;
   }
+  // TODO: review here, maybe additional token required.
   return (
     otherDelims(value, index) ||
     EQ(value, index) ||
     COLON(value, index) ||
     AT(value, index) ||
+    quotationMark(value, index) ||
     pctEncodedNoSQUOTE(value, index) ||
     index
   );
diff --git a/test/__snapshots__/filter.spec.ts.snap b/test/__snapshots__/filter.spec.ts.snap
new file mode 100644
index 0000000..be83e9e
--- /dev/null
+++ b/test/__snapshots__/filter.spec.ts.snap
@@ -0,0 +1,127 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`Filter Test Suite shuold support filter with double quote 1`] = `"$filter=key eq 'val\\"'"`;
+
+exports[`Filter Test Suite shuold support filter with double quote 2`] = `
+Token {
+  "next": 21,
+  "position": 0,
+  "raw": "$filter=key eq 'val\\"'",
+  "type": "QueryOptions",
+  "value": Object {
+    "options": Array [
+      Token {
+        "next": 21,
+        "position": 0,
+        "raw": "$filter=key eq 'val\\"'",
+        "type": "Filter",
+        "value": Token {
+          "next": 21,
+          "position": 8,
+          "raw": "key eq 'val\\"'",
+          "type": "EqualsExpression",
+          "value": Object {
+            "left": Token {
+              "next": 11,
+              "position": 8,
+              "raw": "key",
+              "type": "FirstMemberExpression",
+              "value": Token {
+                "next": 11,
+                "position": 8,
+                "raw": "key",
+                "type": "MemberExpression",
+                "value": Token {
+                  "next": 11,
+                  "position": 8,
+                  "raw": "key",
+                  "type": "PropertyPathExpression",
+                  "value": Token {
+                    "next": 11,
+                    "position": 8,
+                    "raw": "key",
+                    "type": "ODataIdentifier",
+                    "value": Object {
+                      "name": "key",
+                    },
+                  },
+                },
+              },
+            },
+            "right": Token {
+              "next": 21,
+              "position": 15,
+              "raw": "'val\\"'",
+              "type": "Literal",
+              "value": "Edm.String",
+            },
+          },
+        },
+      },
+    ],
+  },
+}
+`;
+
+exports[`Filter Test Suite shuold support filter without double quote 1`] = `"$filter=key eq 'val'"`;
+
+exports[`Filter Test Suite shuold support filter without double quote 2`] = `
+Token {
+  "next": 20,
+  "position": 0,
+  "raw": "$filter=key eq 'val'",
+  "type": "QueryOptions",
+  "value": Object {
+    "options": Array [
+      Token {
+        "next": 20,
+        "position": 0,
+        "raw": "$filter=key eq 'val'",
+        "type": "Filter",
+        "value": Token {
+          "next": 20,
+          "position": 8,
+          "raw": "key eq 'val'",
+          "type": "EqualsExpression",
+          "value": Object {
+            "left": Token {
+              "next": 11,
+              "position": 8,
+              "raw": "key",
+              "type": "FirstMemberExpression",
+              "value": Token {
+                "next": 11,
+                "position": 8,
+                "raw": "key",
+                "type": "MemberExpression",
+                "value": Token {
+                  "next": 11,
+                  "position": 8,
+                  "raw": "key",
+                  "type": "PropertyPathExpression",
+                  "value": Token {
+                    "next": 11,
+                    "position": 8,
+                    "raw": "key",
+                    "type": "ODataIdentifier",
+                    "value": Object {
+                      "name": "key",
+                    },
+                  },
+                },
+              },
+            },
+            "right": Token {
+              "next": 20,
+              "position": 15,
+              "raw": "'val'",
+              "type": "Literal",
+              "value": "Edm.String",
+            },
+          },
+        },
+      },
+    ],
+  },
+}
+`;
diff --git a/test/filter.spec.ts b/test/filter.spec.ts
index bf8e3e0..80c46ae 100644
--- a/test/filter.spec.ts
+++ b/test/filter.spec.ts
@@ -1,6 +1,6 @@
 import { get } from '@newdash/newdash';
 import { Edm } from '@odata/metadata';
-import { defaultParser, ODataFilter } from '../src';
+import { defaultParser, ODataFilter, ODataParam } from '../src';
 
 
 describe('Filter Test Suite', () => {
@@ -17,8 +17,24 @@ describe('Filter Test Suite', () => {
     const ast = defaultParser.query("$filter=A eq 702dac82-923d-4958-805b-ca41c593d74f and B eq 'strValue'");
     expect(ast).not.toBeNull();
     expect(get(ast, 'value.options[0].value.value.left.value.right.value')).toBe(Edm.Guid.className);
-    expect(get(ast,'value.options[0].value.value.right.value.right.value')).toBe(Edm.String.className);
+    expect(get(ast, 'value.options[0].value.value.right.value.right.value')).toBe(Edm.String.className);
   });
+  
+  it('shuold support filter without double quote', () => {
+    const filter = ODataFilter.New().field("key").eq('val')
+    const filterStr = ODataParam.New().filter(filter).toString()
+    expect(filterStr).toMatchSnapshot()
+    const ast = defaultParser.query(filterStr)
+    expect(ast).toMatchSnapshot()
+  })
+
+  it('shuold support filter with double quote', () => {
+    const filter = ODataFilter.New().field("key").eq('val"')
+    const filterStr = ODataParam.New().filter(filter).toString()
+    expect(filterStr).toMatchSnapshot()
+    const ast = defaultParser.query(filterStr)
+    expect(ast).toMatchSnapshot()
+  })
 
   it('should support complex filter', () => {