diff --git a/src/parsing/dates/dates-equals.spec.ts b/src/parsing/dates/dates-equals.spec.ts
index d044bf0..cb90319 100644
--- a/src/parsing/dates/dates-equals.spec.ts
+++ b/src/parsing/dates/dates-equals.spec.ts
@@ -50,11 +50,11 @@ describe('dates-equals', () => {
   });
 
   describe('not', () => {
-    const parser = Is.date.not.equals('2000-01-01');
+    const notParser = Is.date.not.equals('2000-01-01');
 
     it('success', () => {
       const value = parseDate('3000-01-01');
-      const result = parser.parse(value);
+      const result = notParser.parse(value);
 
       expect(result.errors).toEqual(ParseErrors.empty);
       expect(result.value).toEqual(value);
@@ -62,7 +62,7 @@ describe('dates-equals', () => {
 
     it('failure', () => {
       const value = parseDate('2000-01-01');
-      const result = parser.parse(value);
+      const result = notParser.parse(value);
 
       expect(result.errors).toEqual(ParseErrors.not(ParseErrors.equals(value)));
       expect(result.value).toEqual(value);
diff --git a/src/parsing/json/IJson.ts b/src/parsing/json/IJson.ts
index 3794e82..8912cfe 100644
--- a/src/parsing/json/IJson.ts
+++ b/src/parsing/json/IJson.ts
@@ -6,7 +6,7 @@ export namespace IJson {
 
     export interface Parser<T = unknown> extends IParser<T> {
 
-        readonly for: <T>(schema: ComplexSchema<T>) => IComplex.Parser<T>;
-        readonly use: <T>(parser: IParser<T>) => IParser<T>;
+        readonly for: <U>(schema: ComplexSchema<U>) => IComplex.Parser<U>;
+        readonly use: <U>(parser: IParser<U>) => IParser<U>;
     }
 }
diff --git a/src/parsing/numbers/numbers-float-anyOf.spec.ts b/src/parsing/numbers/numbers-float-anyOf.spec.ts
index 4f13dcd..fcf0749 100644
--- a/src/parsing/numbers/numbers-float-anyOf.spec.ts
+++ b/src/parsing/numbers/numbers-float-anyOf.spec.ts
@@ -20,11 +20,11 @@ describe('numbers-float-anyOf', () => {
   });
 
   describe('not', () => {
-    const parser = Is.float.not.anyOf(anyOf);
+    const notParser = Is.float.not.anyOf(anyOf);
 
     it('success', () => {
       const value = 1;
-      const result = parser.parse(value);
+      const result = notParser.parse(value);
 
       expect(result.errors).toEqual(ParseErrors.empty);
       expect(result.value).toEqual(value);
@@ -32,7 +32,7 @@ describe('numbers-float-anyOf', () => {
 
     it('failure', () => {
       const value = anyOf[0];
-      const result = parser.parse(value);
+      const result = notParser.parse(value);
 
       expect(result.errors).toEqual(ParseErrors.not(ParseErrors.anyOf(anyOf)));
       expect(result.value).toEqual(value);
diff --git a/src/parsing/numbers/numbers-float-equals.spec.ts b/src/parsing/numbers/numbers-float-equals.spec.ts
index 7853830..31c2a3b 100644
--- a/src/parsing/numbers/numbers-float-equals.spec.ts
+++ b/src/parsing/numbers/numbers-float-equals.spec.ts
@@ -49,11 +49,11 @@ describe('numbers-float-equals', () => {
   });
 
   describe('not', () => {
-    const parser = Is.float.not.equals(10);
+    const notParser = Is.float.not.equals(10);
 
     it('success', () => {
       const value = 9;
-      const result = parser.parse(value);
+      const result = notParser.parse(value);
 
       expect(result.errors).toEqual(ParseErrors.empty);
       expect(result.value).toEqual(value);
@@ -61,7 +61,7 @@ describe('numbers-float-equals', () => {
 
     it('failure', () => {
       const value = 10;
-      const result = parser.parse(value);
+      const result = notParser.parse(value);
 
       expect(result.errors).toEqual(ParseErrors.not(ParseErrors.equals(value)));
       expect(result.value).toEqual(value);
diff --git a/src/parsing/strings/strings-equals.spec.ts b/src/parsing/strings/strings-equals.spec.ts
index 4f9a8ee..8e7d49d 100644
--- a/src/parsing/strings/strings-equals.spec.ts
+++ b/src/parsing/strings/strings-equals.spec.ts
@@ -21,9 +21,9 @@ describe('strings-equals', () => {
   });
 
   it('success ignore case', () => {
-    const parser = Is.string.equals(expectedValue, true);
+    const ignoreCaseParser = Is.string.equals(expectedValue, true);
     const value = expectedValue.toUpperCase();
-    const result = parser.parse(value);
+    const result = ignoreCaseParser.parse(value);
 
     expect(result.errors).toEqual(ParseErrors.empty);
     expect(result.value).toEqual(value);