diff --git a/src/Assert.php b/src/Assert.php
index f02b8c9..ed11f40 100644
--- a/src/Assert.php
+++ b/src/Assert.php
@@ -889,7 +889,7 @@ public static function notSame($value, $expect, $message = '')
      */
     public static function greaterThan($value, $limit, $message = '')
     {
-        if ($value <= $limit) {
+        if (!($value > $limit)) {
             static::reportInvalidArgument(\sprintf(
                 $message ?: 'Expected a value greater than %2$s. Got: %s',
                 static::valueToString($value),
@@ -909,7 +909,7 @@ public static function greaterThan($value, $limit, $message = '')
      */
     public static function greaterThanEq($value, $limit, $message = '')
     {
-        if ($value < $limit) {
+        if (!($value >= $limit)) {
             static::reportInvalidArgument(\sprintf(
                 $message ?: 'Expected a value greater than or equal to %2$s. Got: %s',
                 static::valueToString($value),
@@ -929,7 +929,7 @@ public static function greaterThanEq($value, $limit, $message = '')
      */
     public static function lessThan($value, $limit, $message = '')
     {
-        if ($value >= $limit) {
+        if (!$value < $limit) {
             static::reportInvalidArgument(\sprintf(
                 $message ?: 'Expected a value less than %2$s. Got: %s',
                 static::valueToString($value),
@@ -949,7 +949,7 @@ public static function lessThan($value, $limit, $message = '')
      */
     public static function lessThanEq($value, $limit, $message = '')
     {
-        if ($value > $limit) {
+        if (!($value <= $limit)) {
             static::reportInvalidArgument(\sprintf(
                 $message ?: 'Expected a value less than or equal to %2$s. Got: %s',
                 static::valueToString($value),
@@ -972,7 +972,7 @@ public static function lessThanEq($value, $limit, $message = '')
      */
     public static function range($value, $min, $max, $message = '')
     {
-        if ($value < $min || $value > $max) {
+        if (!($value >= $min) || !($value <= $max)) {
             static::reportInvalidArgument(\sprintf(
                 $message ?: 'Expected a value between %2$s and %3$s. Got: %s',
                 static::valueToString($value),
@@ -1401,7 +1401,7 @@ public static function length($value, $length, $message = '')
      */
     public static function minLength($value, $min, $message = '')
     {
-        if (static::strlen($value) < $min) {
+        if (!(static::strlen($value) >= $min)) {
             static::reportInvalidArgument(\sprintf(
                 $message ?: 'Expected a value to contain at least %2$s characters. Got: %s',
                 static::valueToString($value),
@@ -1423,7 +1423,7 @@ public static function minLength($value, $min, $message = '')
      */
     public static function maxLength($value, $max, $message = '')
     {
-        if (static::strlen($value) > $max) {
+        if (!(static::strlen($value) <= $max)) {
             static::reportInvalidArgument(\sprintf(
                 $message ?: 'Expected a value to contain at most %2$s characters. Got: %s',
                 static::valueToString($value),
@@ -1448,7 +1448,7 @@ public static function lengthBetween($value, $min, $max, $message = '')
     {
         $length = static::strlen($value);
 
-        if ($length < $min || $length > $max) {
+        if (!($length >= $min) || !($length <= $max)) {
             static::reportInvalidArgument(\sprintf(
                 $message ?: 'Expected a value to contain between %2$s and %3$s characters. Got: %s',
                 static::valueToString($value),
@@ -1805,7 +1805,7 @@ public static function count($array, $number, $message = '')
      */
     public static function minCount($array, $min, $message = '')
     {
-        if (\count($array) < $min) {
+        if (!(\count($array) >= $min)) {
             static::reportInvalidArgument(\sprintf(
                 $message ?: 'Expected an array to contain at least %2$d elements. Got: %d',
                 \count($array),
@@ -1825,7 +1825,7 @@ public static function minCount($array, $min, $message = '')
      */
     public static function maxCount($array, $max, $message = '')
     {
-        if (\count($array) > $max) {
+        if (!(\count($array) <= $max)) {
             static::reportInvalidArgument(\sprintf(
                 $message ?: 'Expected an array to contain at most %2$d elements. Got: %d',
                 \count($array),
@@ -1848,7 +1848,7 @@ public static function countBetween($array, $min, $max, $message = '')
     {
         $count = \count($array);
 
-        if ($count < $min || $count > $max) {
+        if (!($count >= $min) || !($count <= $max)) {
             static::reportInvalidArgument(\sprintf(
                 $message ?: 'Expected an array to contain between %2$d and %3$d elements. Got: %d',
                 $count,
diff --git a/tests/AssertTest.php b/tests/AssertTest.php
index 87a1bb1..0008be7 100644
--- a/tests/AssertTest.php
+++ b/tests/AssertTest.php
@@ -233,18 +233,34 @@ public function getTests()
             array('notSame', array(1, true), true),
             array('greaterThan', array(1, 0), true),
             array('greaterThan', array(0, 0), false),
+            array('greaterThan', array(NAN, 1), false),
+            array('greaterThan', array(1, NAN), false),
+            array('greaterThan', array(NAN, NAN), false),
             array('greaterThanEq', array(2, 1), true),
             array('greaterThanEq', array(1, 1), true),
             array('greaterThanEq', array(0, 1), false),
+            array('greaterThanEq', array(NAN, 1), false),
+            array('greaterThanEq', array(1, NAN), false),
+            array('greaterThanEq', array(NAN, NAN), false),
             array('lessThan', array(0, 1), true),
             array('lessThan', array(1, 1), false),
+            array('lessThan', array(NAN, 1), false),
+            array('lessThan', array(1, NAN), false),
+            array('lessThan', array(NAN, NAN), false),
             array('lessThanEq', array(0, 1), true),
             array('lessThanEq', array(1, 1), true),
             array('lessThanEq', array(2, 1), false),
+            array('lessThanEq', array(NAN, 1), false),
+            array('lessThanEq', array(1, NAN), false),
+            array('lessThanEq', array(NAN, NAN), false),
             array('range', array(1, 1, 2), true),
             array('range', array(2, 1, 2), true),
             array('range', array(0, 1, 2), false),
             array('range', array(3, 1, 2), false),
+            array('range', array(NAN, 1, 2), false),
+            array('range', array(2, NAN, 2), false),
+            array('range', array(2, 1, NAN), false),
+            array('range', array(2, NAN, NAN), false),
             array('oneOf', array(1, array(1, 2, 3)), true),
             array('oneOf', array(1, array('1', '2', '3')), false),
             array('inArray', array(1, array(1, 2, 3)), true),
@@ -390,15 +406,18 @@ public function getTests()
             array('upper', array(''), false),
             array('length', array('abcd', 4), true),
             array('length', array('abc', 4), false),
+            array('length', array('abc', NAN), false),
             array('length', array('abcde', 4), false),
             array('length', array('äbcd', 4), true, true),
             array('length', array('äbc', 4), false, true),
             array('length', array('äbcde', 4), false, true),
             array('length', array('あbcd', 4), true, true), // 'HIRAGANA LETTER A' (U+3042)
+            array('length', array('あbcd', 4), NAN, true),
             array('length', array('あbc', 4), false, true),
             array('length', array('あbcde', 4), false, true),
             array('minLength', array('abcd', 4), true),
             array('minLength', array('abcde', 4), true),
+            array('minLength', array('abcde', NAN), false),
             array('minLength', array('abc', 4), false),
             array('minLength', array('äbcd', 4), true, true),
             array('minLength', array('äbcde', 4), true, true),
@@ -408,16 +427,21 @@ public function getTests()
             array('minLength', array('あbc', 4), false, true),
             array('maxLength', array('abcd', 4), true),
             array('maxLength', array('abc', 4), true),
+            array('maxLength', array('abc', NAN), false),
             array('maxLength', array('abcde', 4), false),
             array('maxLength', array('äbcd', 4), true, true),
             array('maxLength', array('äbc', 4), true, true),
             array('maxLength', array('äbcde', 4), false, true),
             array('maxLength', array('あbcd', 4), true, true),
             array('maxLength', array('あbc', 4), true, true),
+            array('maxLength', array('あbc', NAN), false, true),
             array('maxLength', array('あbcde', 4), false, true),
             array('lengthBetween', array('abcd', 3, 5), true),
             array('lengthBetween', array('abc', 3, 5), true),
             array('lengthBetween', array('abcde', 3, 5), true),
+            array('lengthBetween', array('abcde', 3, NAN), false),
+            array('lengthBetween', array('abcde', NAN, 5), false),
+            array('lengthBetween', array('abcde', NAN, NAN), false),
             array('lengthBetween', array('ab', 3, 5), false),
             array('lengthBetween', array('abcdef', 3, 5), false),
             array('lengthBetween', array('äbcd', 3, 5), true, true),
@@ -428,6 +452,9 @@ public function getTests()
             array('lengthBetween', array('あbcd', 3, 5), true, true),
             array('lengthBetween', array('あbc', 3, 5), true, true),
             array('lengthBetween', array('あbcde', 3, 5), true, true),
+            array('lengthBetween', array('あbcde', NAN, 5), false, true),
+            array('lengthBetween', array('あbcde', 3, NAN), false, true),
+            array('lengthBetween', array('あbcde', NAN, NAN), false, true),
             array('lengthBetween', array('あb', 3, 5), false, true),
             array('lengthBetween', array('あbcdef', 3, 5), false, true),
             array('fileExists', array(__FILE__), true),
@@ -486,18 +513,24 @@ public function getTests()
             array('validArrayKey', array(new ToStringClass('testString')), false),
             array('validArrayKey', array(self::getResource()), false),
             array('count', array(array(0, 1, 2), 3), true),
+            array('count', array(array(0, 1, 2), NAN), false),
             array('count', array(array(0, 1, 2), 2), false),
             array('minCount', array(array(0), 2), false),
             array('minCount', array(array(0, 1), 2), true),
             array('minCount', array(array(0, 1, 2), 2), true),
+            array('minCount', array(array(0, 1, 2), NAN), false),
             array('maxCount', array(array(0, 1, 2), 2), false),
             array('maxCount', array(array(0, 1), 2), true),
             array('maxCount', array(array(0), 2), true),
+            array('maxCount', array(array(0), NAN), false),
             array('countBetween', array(array(0, 1, 2), 4, 5), false),
             array('countBetween', array(array(0, 1, 2), 3, 5), true),
             array('countBetween', array(array(0, 1, 2), 1, 2), false),
             array('countBetween', array(array(0, 1, 2), 2, 5), true),
             array('countBetween', array(array(0, 1, 2), 2, 3), true),
+            array('countBetween', array(array(0, 1, 2), NAN, 3), false),
+            array('countBetween', array(array(0, 1, 2), 2, NAN), false),
+            array('countBetween', array(array(0, 1, 2), NAN, NAN), false),
             array('isList', array(array(1, 2, 3)), true),
             array('isList', array(array()), true),
             array('isList', array(array(0 => 1, 2 => 3)), false),