diff --git a/assert/assertion_format.go b/assert/assertion_format.go
index 56a7779..679f279 100644
--- a/assert/assertion_format.go
+++ b/assert/assertion_format.go
@@ -45,7 +45,8 @@ func Emptyf(t TestingT, object interface{}, msg string, args ...interface{}) boo
 // Returns whether the assertion was successful (true) or not (false).
 //
 // Pointer variable equality is determined based on the equality of the
-// referenced values (as opposed to the memory addresses).
+// referenced values (as opposed to the memory addresses). Function equality
+// cannot be determined and will always fail.
 func Equalf(t TestingT, expected interface{}, actual interface{}, msg string, args ...interface{}) bool {
 	return Equal(t, expected, actual, append([]interface{}{msg}, args...)...)
 }
diff --git a/assert/assertion_forward.go b/assert/assertion_forward.go
index 2c09998..cedbdee 100644
--- a/assert/assertion_forward.go
+++ b/assert/assertion_forward.go
@@ -72,7 +72,8 @@ func (a *Assertions) Emptyf(object interface{}, msg string, args ...interface{})
 // Returns whether the assertion was successful (true) or not (false).
 //
 // Pointer variable equality is determined based on the equality of the
-// referenced values (as opposed to the memory addresses).
+// referenced values (as opposed to the memory addresses). Function equality
+// cannot be determined and will always fail.
 func (a *Assertions) Equal(expected interface{}, actual interface{}, msgAndArgs ...interface{}) bool {
 	return Equal(a.t, expected, actual, msgAndArgs...)
 }
@@ -126,7 +127,8 @@ func (a *Assertions) EqualValuesf(expected interface{}, actual interface{}, msg
 // Returns whether the assertion was successful (true) or not (false).
 //
 // Pointer variable equality is determined based on the equality of the
-// referenced values (as opposed to the memory addresses).
+// referenced values (as opposed to the memory addresses). Function equality
+// cannot be determined and will always fail.
 func (a *Assertions) Equalf(expected interface{}, actual interface{}, msg string, args ...interface{}) bool {
 	return Equalf(a.t, expected, actual, msg, args...)
 }
diff --git a/assert/assertions.go b/assert/assertions.go
index 2826738..9fe00d6 100644
--- a/assert/assertions.go
+++ b/assert/assertions.go
@@ -4,6 +4,7 @@ import (
 	"bufio"
 	"bytes"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"math"
 	"reflect"
@@ -300,8 +301,13 @@ func IsType(t TestingT, expectedType interface{}, object interface{}, msgAndArgs
 // Returns whether the assertion was successful (true) or not (false).
 //
 // Pointer variable equality is determined based on the equality of the
-// referenced values (as opposed to the memory addresses).
+// referenced values (as opposed to the memory addresses). Function equality
+// cannot be determined and will always fail.
 func Equal(t TestingT, expected, actual interface{}, msgAndArgs ...interface{}) bool {
+	if err := validateEqualArgs(expected, actual); err != nil {
+		return Fail(t, fmt.Sprintf("Invalid operation: %#v == %#v (%s)",
+			expected, actual, err), msgAndArgs...)
+	}
 
 	if !ObjectsAreEqual(expected, actual) {
 		diff := diff(expected, actual)
@@ -575,6 +581,10 @@ func False(t TestingT, value bool, msgAndArgs ...interface{}) bool {
 // Pointer variable equality is determined based on the equality of the
 // referenced values (as opposed to the memory addresses).
 func NotEqual(t TestingT, expected, actual interface{}, msgAndArgs ...interface{}) bool {
+	if err := validateEqualArgs(expected, actual); err != nil {
+		return Fail(t, fmt.Sprintf("Invalid operation: %#v != %#v (%s)",
+			expected, actual, err), msgAndArgs...)
+	}
 
 	if ObjectsAreEqual(expected, actual) {
 		return Fail(t, fmt.Sprintf("Should not be: %#v\n", actual), msgAndArgs...)
@@ -1155,6 +1165,22 @@ func diff(expected interface{}, actual interface{}) string {
 	return "\n\nDiff:\n" + diff
 }
 
+// validateEqualArgs checks whether provided arguments can be safely used in the
+// Equal/NotEqual functions.
+func validateEqualArgs(expected, actual interface{}) error {
+	if isFunction(expected) || isFunction(actual) {
+		return errors.New("cannot take func type as argument")
+	}
+	return nil
+}
+
+func isFunction(arg interface{}) bool {
+	if arg == nil {
+		return false
+	}
+	return reflect.TypeOf(arg).Kind() == reflect.Func
+}
+
 var spewConfig = spew.ConfigState{
 	Indent:                  " ",
 	DisablePointerAddresses: true,
diff --git a/assert/assertions_test.go b/assert/assertions_test.go
index 96ecf33..0009be5 100644
--- a/assert/assertions_test.go
+++ b/assert/assertions_test.go
@@ -396,8 +396,8 @@ func TestNotEqual(t *testing.T) {
 	}
 	funcA := func() int { return 23 }
 	funcB := func() int { return 42 }
-	if !NotEqual(mockT, funcA, funcB) {
-		t.Error("NotEqual should return true")
+	if NotEqual(mockT, funcA, funcB) {
+		t.Error("NotEqual should return false")
 	}
 
 	if NotEqual(mockT, "Hello World", "Hello World") {
@@ -1375,3 +1375,8 @@ func BenchmarkBytesEqual(b *testing.B) {
 		Equal(mockT, s, s2)
 	}
 }
+
+func TestEqualArgsValidation(t *testing.T) {
+	err := validateEqualArgs(time.Now, time.Now)
+	EqualError(t, err, "cannot take func type as argument")
+}
diff --git a/require/require.go b/require/require.go
index f990eaf..cc39791 100644
--- a/require/require.go
+++ b/require/require.go
@@ -85,7 +85,8 @@ func Emptyf(t TestingT, object interface{}, msg string, args ...interface{}) {
 // Returns whether the assertion was successful (true) or not (false).
 //
 // Pointer variable equality is determined based on the equality of the
-// referenced values (as opposed to the memory addresses).
+// referenced values (as opposed to the memory addresses). Function equality
+// cannot be determined and will always fail.
 func Equal(t TestingT, expected interface{}, actual interface{}, msgAndArgs ...interface{}) {
 	if !assert.Equal(t, expected, actual, msgAndArgs...) {
 		t.FailNow()
@@ -149,7 +150,8 @@ func EqualValuesf(t TestingT, expected interface{}, actual interface{}, msg stri
 // Returns whether the assertion was successful (true) or not (false).
 //
 // Pointer variable equality is determined based on the equality of the
-// referenced values (as opposed to the memory addresses).
+// referenced values (as opposed to the memory addresses). Function equality
+// cannot be determined and will always fail.
 func Equalf(t TestingT, expected interface{}, actual interface{}, msg string, args ...interface{}) {
 	if !assert.Equalf(t, expected, actual, msg, args...) {
 		t.FailNow()
diff --git a/require/require_forward.go b/require/require_forward.go
index 1a0de74..fadac2f 100644
--- a/require/require_forward.go
+++ b/require/require_forward.go
@@ -73,7 +73,8 @@ func (a *Assertions) Emptyf(object interface{}, msg string, args ...interface{})
 // Returns whether the assertion was successful (true) or not (false).
 //
 // Pointer variable equality is determined based on the equality of the
-// referenced values (as opposed to the memory addresses).
+// referenced values (as opposed to the memory addresses). Function equality
+// cannot be determined and will always fail.
 func (a *Assertions) Equal(expected interface{}, actual interface{}, msgAndArgs ...interface{}) {
 	Equal(a.t, expected, actual, msgAndArgs...)
 }
@@ -127,7 +128,8 @@ func (a *Assertions) EqualValuesf(expected interface{}, actual interface{}, msg
 // Returns whether the assertion was successful (true) or not (false).
 //
 // Pointer variable equality is determined based on the equality of the
-// referenced values (as opposed to the memory addresses).
+// referenced values (as opposed to the memory addresses). Function equality
+// cannot be determined and will always fail.
 func (a *Assertions) Equalf(expected interface{}, actual interface{}, msg string, args ...interface{}) {
 	Equalf(a.t, expected, actual, msg, args...)
 }