diff --git a/rules/PHPUnit100/Rector/Class_/AddProphecyTraitRector.php b/rules/PHPUnit100/Rector/Class_/AddProphecyTraitRector.php
index 7c4cff55..fd4b5d46 100644
--- a/rules/PHPUnit100/Rector/Class_/AddProphecyTraitRector.php
+++ b/rules/PHPUnit100/Rector/Class_/AddProphecyTraitRector.php
@@ -119,6 +119,16 @@ private function shouldSkipClass(Class_ $class): bool
             return true;
         }
 
+        // structural check first, so the rule stays idempotent even when the class reflection is
+        // not yet aware of a trait added on a previous pass
+        foreach ($class->getTraitUses() as $traitUse) {
+            foreach ($traitUse->traits as $trait) {
+                if ($this->isName($trait, ProphecyClassName::PROPHECY_TRAIT)) {
+                    return true;
+                }
+            }
+        }
+
         $classReflection = $this->reflectionResolver->resolveClassReflection($class);
         if (! $classReflection instanceof ClassReflection) {
             return false;