diff --git a/src/main/java/org/refactoringminer/astDiff/matchers/wrappers/FieldDeclarationMatcher.java b/src/main/java/org/refactoringminer/astDiff/matchers/wrappers/FieldDeclarationMatcher.java
index 5de0b7639c..17387ee51a 100644
--- a/src/main/java/org/refactoringminer/astDiff/matchers/wrappers/FieldDeclarationMatcher.java
+++ b/src/main/java/org/refactoringminer/astDiff/matchers/wrappers/FieldDeclarationMatcher.java
@@ -98,10 +98,12 @@ private void processFieldDeclaration(Tree srcTree, Tree dstTree, UMLAttribute sr
         new JavaDocMatcher(optimizationData, srcUMLAttribute.getJavadoc(), dstUMLAttribute.getJavadoc(), umlJavadocDiff)
                 .match(srcTree, dstTree, mappingStore);
         if (srcVarDeclaration != null && dstVarDeclaration != null)
-            mappingStore.addMapping(srcVarDeclaration.getChild(0),dstVarDeclaration.getChild(0));
+            if (!srcVarDeclaration.getChildren().isEmpty() && !dstVarDeclaration.getChildren().isEmpty())
+                mappingStore.addMapping(srcVarDeclaration.getChild(0),dstVarDeclaration.getChild(0));
     }
 
     private void matchFieldAllModifiers(Tree srcFieldDeclaration, Tree dstFieldDeclaration, UMLAttribute srcUMLAttribute, UMLAttribute dstUMLAttribute, ExtendedMultiMappingStore mappingStore) {
+        if (srcFieldDeclaration == null || dstFieldDeclaration == null) return;
         matchModifiersForField(srcFieldDeclaration,dstFieldDeclaration,srcUMLAttribute.getVisibility().toString(),dstUMLAttribute.getVisibility().toString(),mappingStore);
         if (srcUMLAttribute.isFinal() && dstUMLAttribute.isFinal())
             matchModifierForField(srcFieldDeclaration,dstFieldDeclaration,Constants.FINAL,mappingStore);
diff --git a/src/main/java/org/refactoringminer/astDiff/utils/TreeUtilFunctions.java b/src/main/java/org/refactoringminer/astDiff/utils/TreeUtilFunctions.java
index bbe33ca14b..28b714615a 100644
--- a/src/main/java/org/refactoringminer/astDiff/utils/TreeUtilFunctions.java
+++ b/src/main/java/org/refactoringminer/astDiff/utils/TreeUtilFunctions.java
@@ -298,9 +298,10 @@ public static boolean isFromType(Tree t1, String type) {
 		return t1.getType().name.equals(type);
 	}
 
-	public static Tree findFirstByType(Tree srcFieldDeclaration, String typeName) {
+	public static Tree findFirstByType(Tree inputTree, String typeName) {
+		if (inputTree == null) return null;
 		Tree fieldAnnotation = null;
-		for (Tree child : srcFieldDeclaration.getChildren()) {
+		for (Tree child : inputTree.getChildren()) {
 			if (isFromType(child, typeName)) {
 				fieldAnnotation = child;
 				break;