diff --git a/composer.json b/composer.json
index 8a2de30e..ee507510 100644
--- a/composer.json
+++ b/composer.json
@@ -36,6 +36,9 @@
         "json-schema/JSON-Schema-Test-Suite": "1.2.0",
         "phpunit/phpunit": "^4.8.35"
     },
+    "suggest": {
+        "ext-bcmath": "For better number assertion, see issue #588."
+    },
     "extra": {
         "branch-alias": {
             "dev-master": "5.0.x-dev"
diff --git a/src/JsonSchema/Constraints/TypeConstraint.php b/src/JsonSchema/Constraints/TypeConstraint.php
index ff4eba71..af7d774f 100644
--- a/src/JsonSchema/Constraints/TypeConstraint.php
+++ b/src/JsonSchema/Constraints/TypeConstraint.php
@@ -290,8 +290,16 @@ protected function toNumber($value)
     protected function toInteger($value)
     {
         $numberValue = $this->toNumber($value);
-        if (is_numeric($numberValue) && (int) $numberValue == $numberValue) {
-            return (int) $numberValue; // cast to number
+        if (is_numeric($numberValue)) {
+            if (function_exists('bcsub')) {
+                if (0 === bcsub((int) $numberValue, $numberValue)) {
+                    return (int) $numberValue;
+                }
+            }
+
+            if ((int) $numberValue == $numberValue) {
+                return (int) $numberValue; // cast to number
+            }
         }
 
         return $value;