diff --git a/rules-tests/PHPUnit100/Rector/Class_/AddProphecyTraitRector/Fixture/skip_non_test_class.php.inc b/rules-tests/PHPUnit100/Rector/Class_/AddProphecyTraitRector/Fixture/skip_non_test_class.php.inc
new file mode 100644
index 00000000..d2dcedf7
--- /dev/null
+++ b/rules-tests/PHPUnit100/Rector/Class_/AddProphecyTraitRector/Fixture/skip_non_test_class.php.inc
@@ -0,0 +1,11 @@
+<?php
+
+namespace Rector\PHPUnit\Tests\PHPUnit100\Rector\Class_\AddProphecyTraitRector\Fixture;
+
+final class SomeService
+{
+    public function run(): void
+    {
+        $prophecy = $this->prophesize(\AnInterface::class);
+    }
+}
diff --git a/rules/PHPUnit100/Rector/Class_/AddProphecyTraitRector.php b/rules/PHPUnit100/Rector/Class_/AddProphecyTraitRector.php
index 18996a8d..136c413c 100644
--- a/rules/PHPUnit100/Rector/Class_/AddProphecyTraitRector.php
+++ b/rules/PHPUnit100/Rector/Class_/AddProphecyTraitRector.php
@@ -106,6 +106,10 @@ public function refactor(Node $node): ?Node
 
     private function shouldSkipClass(Class_ $class): bool
     {
+        if (! $this->testsNodeAnalyzer->isInTestClass($class)) {
+            return true;
+        }
+
         $hasProphesizeMethodCall = (bool) $this->betterNodeFinder->findFirst(
             $class,
             fn (Node $node): bool => $this->testsNodeAnalyzer->isAssertMethodCallName($node, 'prophesize')