diff --git a/app/Http/ValidationRules/ValidAmount.php b/app/Http/ValidationRules/ValidAmount.php
index 4f5fe1700de3..d2832e83a046 100644
--- a/app/Http/ValidationRules/ValidAmount.php
+++ b/app/Http/ValidationRules/ValidAmount.php
@@ -26,7 +26,8 @@ class ValidAmount implements Rule
      */
     public function passes($attribute, $value)
     {
-        return (bool) is_float($value) || preg_match('#[^0-9]#',$value);
+        return trim($value, '-1234567890.,') === '';
+
     }
 
     /**
diff --git a/tests/Integration/Validation/AmountValidationRuleTest.php b/tests/Integration/Validation/AmountValidationRuleTest.php
new file mode 100644
index 000000000000..82a9b06c0a69
--- /dev/null
+++ b/tests/Integration/Validation/AmountValidationRuleTest.php
@@ -0,0 +1,143 @@
+<?php
+/**
+ * Invoice Ninja (https://invoiceninja.com).
+ *
+ * @link https://github.com/invoiceninja/invoiceninja source repository
+ *
+ * @copyright Copyright (c) 2021. Invoice Ninja LLC (https://invoiceninja.com)
+ *
+ * @license https://opensource.org/licenses/AAL
+ */
+namespace Tests\Integration\Validation;
+
+use App\Http\ValidationRules\ValidAmount;
+use Tests\TestCase;
+
+/**
+ * @test
+ */
+class AmountValidationRuleTest extends TestCase
+{
+
+    public function setUp() :void
+    {
+        parent::setUp();
+
+    }
+
+    public function testSimpleAmountValid()
+    {
+        $rules = [
+            'amount' => [new ValidAmount()]
+        ];
+        
+        $data = [
+            'amount' => 1,
+        ];
+        
+        $v = $this->app['validator']->make($data, $rules);
+        $this->assertTrue($v->passes());
+    }
+
+    public function testInvalidAmountValid()
+    {
+        $rules = [
+            'amount' => [new ValidAmount()]
+        ];
+        
+        $data = [
+            'amount' => "aa",
+        ];
+        
+        $v = $this->app['validator']->make($data, $rules);
+        $this->assertFalse($v->passes());
+    }
+
+    public function testIllegalChars()
+    {
+        $rules = [
+            'amount' => [new ValidAmount()]
+        ];
+        
+        $data = [
+            'amount' => "5+5",
+        ];
+        
+        $v = $this->app['validator']->make($data, $rules);
+        $this->assertFalse($v->passes());
+    }
+
+    public function testIllegalCharsNaked()
+    {
+        $rules = [
+            'amount' => [new ValidAmount()]
+        ];
+        
+        $data = [
+            'amount' => 5+5, //resolves as 10 - but in practice, i believe this amount is wrapped in quotes so interpreted as a string
+        ];
+        
+        $v = $this->app['validator']->make($data, $rules);
+        $this->assertTrue($v->passes());
+    }
+
+
+    public function testinValidScenario1()
+    {
+        $rules = [
+            'amount' => [new ValidAmount()]
+        ];
+        
+        $data = [
+            'amount' => "-10x",
+        ];
+        
+        $v = $this->app['validator']->make($data, $rules);
+        $this->assertFalse($v->passes());
+    }
+
+    public function testValidScenario2()
+    {
+        $rules = [
+            'amount' => [new ValidAmount()]
+        ];
+        
+        $data = [
+            'amount' => -10,
+        ];
+        
+        $v = $this->app['validator']->make($data, $rules);
+        $this->assertTrue($v->passes());
+    }
+
+
+    public function testValidScenario3()
+    {
+        $rules = [
+            'amount' => [new ValidAmount()]
+        ];
+        
+        $data = [
+            'amount' => "-10",
+        ];
+        
+        $v = $this->app['validator']->make($data, $rules);
+        $this->assertTrue($v->passes());
+    }
+
+    public function testInValidScenario4()
+    {
+        $rules = [
+            'amount' => [new ValidAmount()]
+        ];
+        
+        $data = [
+            'amount' => "-0 1",
+        ];
+        
+        $v = $this->app['validator']->make($data, $rules);
+        $this->assertFalse($v->passes());
+    }    
+}
+
+