diff --git a/src/PatternLab/PatternData/Rules/PatternInfoListItemsRule.php b/src/PatternLab/PatternData/Rules/PatternInfoListItemsRule.php
index 275f1178..ecba0b56 100644
--- a/src/PatternLab/PatternData/Rules/PatternInfoListItemsRule.php
+++ b/src/PatternLab/PatternData/Rules/PatternInfoListItemsRule.php
@@ -26,7 +26,7 @@ public function __construct($options) {
 		parent::__construct($options);
 		
 		$this->depthProp  = 3; // 3 means that depth won't be checked
-		$this->extProp    = "json||yaml";
+		$this->extProp    = "json||yaml||yml";
 		$this->isDirProp  = false;
 		$this->isFileProp = true;
 		$this->searchProp = ".listitems.";
diff --git a/src/PatternLab/PatternData/Rules/PatternInfoRule.php b/src/PatternLab/PatternData/Rules/PatternInfoRule.php
index d2509211..b18818d9 100644
--- a/src/PatternLab/PatternData/Rules/PatternInfoRule.php
+++ b/src/PatternLab/PatternData/Rules/PatternInfoRule.php
@@ -26,7 +26,7 @@ public function __construct($options) {
 		parent::__construct($options);
 		
 		$this->depthProp  = 3; // 3 means that depth won't be checked
-		$this->extProp    = "json||yaml";
+		$this->extProp    = "json||yaml||yml";
 		$this->isDirProp  = false;
 		$this->isFileProp = true;
 		$this->searchProp = "";
diff --git a/src/PatternLab/PatternData/Rules/PseudoPatternRule.php b/src/PatternLab/PatternData/Rules/PseudoPatternRule.php
index 242df147..9fee61aa 100644
--- a/src/PatternLab/PatternData/Rules/PseudoPatternRule.php
+++ b/src/PatternLab/PatternData/Rules/PseudoPatternRule.php
@@ -26,7 +26,7 @@ public function __construct($options) {
 		parent::__construct($options);
 
 		$this->depthProp  = 3; // 3 means that depth won't be checked
-		$this->extProp    = "json||yaml";
+		$this->extProp    = "json||yaml||yml";
 		$this->isDirProp  = false;
 		$this->isFileProp = true;
 		$this->searchProp = "~";