diff --git a/assert/assertion_compare_test.go b/assert/assertion_compare_test.go
index da5a33033..6f7db87c8 100644
--- a/assert/assertion_compare_test.go
+++ b/assert/assertion_compare_test.go
@@ -150,7 +150,7 @@ func TestGreater(t *testing.T) {
 	} {
 		out := &outputT{buf: bytes.NewBuffer(nil)}
 		False(t, Greater(out, currCase.less, currCase.greater))
-		Contains(t, string(out.buf.Bytes()), currCase.msg)
+		Contains(t, out.buf.String(), currCase.msg)
 		Contains(t, out.helpers, "github.com/stretchr/testify/assert.Greater")
 	}
 }
@@ -191,7 +191,7 @@ func TestGreaterOrEqual(t *testing.T) {
 	} {
 		out := &outputT{buf: bytes.NewBuffer(nil)}
 		False(t, GreaterOrEqual(out, currCase.less, currCase.greater))
-		Contains(t, string(out.buf.Bytes()), currCase.msg)
+		Contains(t, out.buf.String(), currCase.msg)
 		Contains(t, out.helpers, "github.com/stretchr/testify/assert.GreaterOrEqual")
 	}
 }
@@ -232,7 +232,7 @@ func TestLess(t *testing.T) {
 	} {
 		out := &outputT{buf: bytes.NewBuffer(nil)}
 		False(t, Less(out, currCase.greater, currCase.less))
-		Contains(t, string(out.buf.Bytes()), currCase.msg)
+		Contains(t, out.buf.String(), currCase.msg)
 		Contains(t, out.helpers, "github.com/stretchr/testify/assert.Less")
 	}
 }
@@ -273,7 +273,7 @@ func TestLessOrEqual(t *testing.T) {
 	} {
 		out := &outputT{buf: bytes.NewBuffer(nil)}
 		False(t, LessOrEqual(out, currCase.greater, currCase.less))
-		Contains(t, string(out.buf.Bytes()), currCase.msg)
+		Contains(t, out.buf.String(), currCase.msg)
 		Contains(t, out.helpers, "github.com/stretchr/testify/assert.LessOrEqual")
 	}
 }
@@ -312,7 +312,7 @@ func TestPositive(t *testing.T) {
 	} {
 		out := &outputT{buf: bytes.NewBuffer(nil)}
 		False(t, Positive(out, currCase.e))
-		Contains(t, string(out.buf.Bytes()), currCase.msg)
+		Contains(t, out.buf.String(), currCase.msg)
 		Contains(t, out.helpers, "github.com/stretchr/testify/assert.Positive")
 	}
 }
@@ -351,7 +351,7 @@ func TestNegative(t *testing.T) {
 	} {
 		out := &outputT{buf: bytes.NewBuffer(nil)}
 		False(t, Negative(out, currCase.e))
-		Contains(t, string(out.buf.Bytes()), currCase.msg)
+		Contains(t, out.buf.String(), currCase.msg)
 		Contains(t, out.helpers, "github.com/stretchr/testify/assert.Negative")
 	}
 }
@@ -386,7 +386,7 @@ func Test_compareTwoValuesNotComparableValues(t *testing.T) {
 	}{
 		{v1: CompareStruct{}, v2: CompareStruct{}},
 		{v1: map[string]int{}, v2: map[string]int{}},
-		{v1: make([]int, 5, 5), v2: make([]int, 5, 5)},
+		{v1: make([]int, 5), v2: make([]int, 5)},
 	} {
 		compareResult := compareTwoValues(mockT, currCase.v1, currCase.v2, []CompareType{compareLess, compareEqual, compareGreater}, "testFailMessage")
 		False(t, compareResult)
diff --git a/assert/assertion_order_test.go b/assert/assertion_order_test.go
index 98cbe0eae..7726b82f9 100644
--- a/assert/assertion_order_test.go
+++ b/assert/assertion_order_test.go
@@ -46,7 +46,7 @@ func TestIsIncreasing(t *testing.T) {
 	} {
 		out := &outputT{buf: bytes.NewBuffer(nil)}
 		False(t, IsIncreasing(out, currCase.collection))
-		Contains(t, string(out.buf.Bytes()), currCase.msg)
+		Contains(t, out.buf.String(), currCase.msg)
 	}
 }
 
@@ -91,7 +91,7 @@ func TestIsNonIncreasing(t *testing.T) {
 	} {
 		out := &outputT{buf: bytes.NewBuffer(nil)}
 		False(t, IsNonIncreasing(out, currCase.collection))
-		Contains(t, string(out.buf.Bytes()), currCase.msg)
+		Contains(t, out.buf.String(), currCase.msg)
 	}
 }
 
@@ -136,7 +136,7 @@ func TestIsDecreasing(t *testing.T) {
 	} {
 		out := &outputT{buf: bytes.NewBuffer(nil)}
 		False(t, IsDecreasing(out, currCase.collection))
-		Contains(t, string(out.buf.Bytes()), currCase.msg)
+		Contains(t, out.buf.String(), currCase.msg)
 	}
 }
 
@@ -181,6 +181,6 @@ func TestIsNonDecreasing(t *testing.T) {
 	} {
 		out := &outputT{buf: bytes.NewBuffer(nil)}
 		False(t, IsNonDecreasing(out, currCase.collection))
-		Contains(t, string(out.buf.Bytes()), currCase.msg)
+		Contains(t, out.buf.String(), currCase.msg)
 	}
 }
diff --git a/assert/assertions.go b/assert/assertions.go
index 79a115088..230118b3b 100644
--- a/assert/assertions.go
+++ b/assert/assertions.go
@@ -856,7 +856,7 @@ func NotSubset(t TestingT, list, subset interface{}, msgAndArgs ...interface{})
 		h.Helper()
 	}
 	if subset == nil {
-		return Fail(t, fmt.Sprintf("nil is the empty set which is a subset of every set"), msgAndArgs...)
+		return Fail(t, "nil is the empty set which is a subset of every set", msgAndArgs...)
 	}
 
 	subsetValue := reflect.ValueOf(subset)
@@ -1165,7 +1165,7 @@ func InDelta(t TestingT, expected, actual interface{}, delta float64, msgAndArgs
 	bf, bok := toFloat(actual)
 
 	if !aok || !bok {
-		return Fail(t, fmt.Sprintf("Parameters must be numerical"), msgAndArgs...)
+		return Fail(t, "Parameters must be numerical", msgAndArgs...)
 	}
 
 	if math.IsNaN(af) && math.IsNaN(bf) {
@@ -1173,7 +1173,7 @@ func InDelta(t TestingT, expected, actual interface{}, delta float64, msgAndArgs
 	}
 
 	if math.IsNaN(af) {
-		return Fail(t, fmt.Sprintf("Expected must not be NaN"), msgAndArgs...)
+		return Fail(t, "Expected must not be NaN", msgAndArgs...)
 	}
 
 	if math.IsNaN(bf) {
@@ -1196,7 +1196,7 @@ func InDeltaSlice(t TestingT, expected, actual interface{}, delta float64, msgAn
 	if expected == nil || actual == nil ||
 		reflect.TypeOf(actual).Kind() != reflect.Slice ||
 		reflect.TypeOf(expected).Kind() != reflect.Slice {
-		return Fail(t, fmt.Sprintf("Parameters must be slice"), msgAndArgs...)
+		return Fail(t, "Parameters must be slice", msgAndArgs...)
 	}
 
 	actualSlice := reflect.ValueOf(actual)
@@ -1306,7 +1306,7 @@ func InEpsilonSlice(t TestingT, expected, actual interface{}, epsilon float64, m
 	if expected == nil || actual == nil ||
 		reflect.TypeOf(actual).Kind() != reflect.Slice ||
 		reflect.TypeOf(expected).Kind() != reflect.Slice {
-		return Fail(t, fmt.Sprintf("Parameters must be slice"), msgAndArgs...)
+		return Fail(t, "Parameters must be slice", msgAndArgs...)
 	}
 
 	actualSlice := reflect.ValueOf(actual)
diff --git a/assert/assertions_test.go b/assert/assertions_test.go
index 880f9cc43..0b5b2c187 100644
--- a/assert/assertions_test.go
+++ b/assert/assertions_test.go
@@ -1575,8 +1575,7 @@ func testAutogeneratedFunction() {
 	t := struct {
 		io.Closer
 	}{}
-	var c io.Closer
-	c = t
+	c := t
 	c.Close()
 }
 
@@ -2224,7 +2223,7 @@ func ExampleValueAssertionFunc() {
 
 	dumbParse := func(input string) interface{} {
 		var x interface{}
-		json.Unmarshal([]byte(input), &x)
+		_ = json.Unmarshal([]byte(input), &x)
 		return x
 	}
 
diff --git a/assert/http_assertions_test.go b/assert/http_assertions_test.go
index 991866ac4..413c9714f 100644
--- a/assert/http_assertions_test.go
+++ b/assert/http_assertions_test.go
@@ -122,7 +122,7 @@ func TestHTTPStatusesWrapper(t *testing.T) {
 
 func httpHelloName(w http.ResponseWriter, r *http.Request) {
 	name := r.FormValue("name")
-	w.Write([]byte(fmt.Sprintf("Hello, %s!", name)))
+	_, _ = w.Write([]byte(fmt.Sprintf("Hello, %s!", name)))
 }
 
 func TestHTTPRequestWithNoParams(t *testing.T) {