diff --git a/src/mpIterator.py b/src/mpIterator.py
index d428728..1ada58e 100755
--- a/src/mpIterator.py
+++ b/src/mpIterator.py
@@ -62,16 +62,17 @@ for test_name in [name for name in os.listdir(tests_dir) if os.path.isdir(os.pat
 	# Run validations
 	with open(validation_file, 'r') as f:
 		validations = load(f)
-	for k in validations.keys():
-		# Identify checker class
-		name = k.title().replace("_","")+"Checker"
-		klass= globals()[name]
-		# instantiate checker with validations and test_name
-		checker = klass(validations, test_name, destDir)
-		if checker.check():
-			print checker.logs
-		else:
-			print checker.logs
+	if validations!=None:
+		for k in validations.keys():
+			# Identify checker class
+			name = k.title().replace("_","")+"Checker"
+			klass= globals()[name]
+			# instantiate checker with validations and test_name
+			checker = klass(validations, test_name, destDir)
+			if checker.check():
+				print checker.logs
+			else:
+				print checker.logs
 
 
 
diff --git a/src/mpValidations.py b/src/mpValidations.py
index 6b7722b..563fa99 100644
--- a/src/mpValidations.py
+++ b/src/mpValidations.py
@@ -141,16 +141,17 @@ class Checker:
 	def check(self):
 		is_ok = True
 		self.logs=self.test_id+"\n"
-		for test in self.yml:
-			name=test["test"].title().replace("_","")+"Test"
-			klass = globals()[name]
-			r = klass(test, self.trace)
-			if r.validate():
-				self.logs = self.logs + " *" + self.test_id + " " + r.name() + " SUCCESS\n"
-				self.logs = self.logs +  r.logs
-			else:
-				self.logs = self.logs + " *" + self.test_id + " " + r.name() + " FAIL\n"
-				self.logs = self.logs + r.logs
+		if self.yml!=None:
+			for test in self.yml:
+				name=test["test"].title().replace("_","")+"Test"
+				klass = globals()[name]
+				r = klass(test, self.trace)
+				if r.validate():
+					self.logs = self.logs + " *" + self.test_id + " " + r.name() + " SUCCESS\n"
+					self.logs = self.logs +  r.logs
+				else:
+					self.logs = self.logs + " *" + self.test_id + " " + r.name() + " FAIL\n"
+					self.logs = self.logs + r.logs
 
 # Runs tests based on tcptrace
 # It (in the method inherited from its parent class) instanciates the ...Test class passing it the TcptraceData instance