diff --git a/TimberWinR/Filters/GrokFilter.cs b/TimberWinR/Filters/GrokFilter.cs
index 1477742..9572633 100644
--- a/TimberWinR/Filters/GrokFilter.cs
+++ b/TimberWinR/Filters/GrokFilter.cs
@@ -175,6 +175,11 @@ namespace TimberWinR.Filters
                 // Return true if the fields match:
                 return (Field == p.Field) && (Value == p.Value);
             }
+
+            public override int GetHashCode()
+            {
+                return Field.GetHashCode() + Value.GetHashCode();
+            }
         }
 
         private void ParseAddTags(XElement parent)
diff --git a/TimberWinR/Inputs/FieldDefinitions.cs b/TimberWinR/Inputs/FieldDefinitions.cs
index 0d61655..bee3934 100644
--- a/TimberWinR/Inputs/FieldDefinitions.cs
+++ b/TimberWinR/Inputs/FieldDefinitions.cs
@@ -72,6 +72,11 @@ namespace TimberWinR.Inputs
             // Return true if the fields match:
             return (Name == p.Name) && (FieldType == p.FieldType);
         }
+
+        public override int GetHashCode()
+        {
+            return Name.GetHashCode() + FieldType.GetHashCode();
+        }
     }
 
     public class FieldDefinitions : IEnumerable<FieldDefinition>