diff --git a/Conversion/Converter.cs b/Conversion/Converter.cs
index 04d37af..e64c3d6 100644
--- a/Conversion/Converter.cs
+++ b/Conversion/Converter.cs
@@ -115,7 +115,7 @@ namespace vassago.Conversion
                 }
                 else
                 {
-                    return $"{String.Format("{0:G4}", accumulator)} {normalizedDestUnit}";
+                    return $"{String.Format("{0:G4}", accumulator)} {normalizedDestUnit}s";
                 }
             }
             return "dimensional analysis failure - I know those units but can't find a path between them.";
diff --git a/assets/conversion.json b/assets/conversion.json
index 9687fea..a31a538 100644
--- a/assets/conversion.json
+++ b/assets/conversion.json
@@ -36,6 +36,13 @@
                 "metre"
             ]
         },
+        {
+            "canonical":"mm",
+            "aliases": [
+                "millimeter",
+                "millimetre"
+            ]
+        },
         {
             "canonical":"km",
             "aliases": [
@@ -230,6 +237,7 @@
         {"item1":"mi", "item2":"ft", "factor":5280},
         {"item1":"m", "item2":"in", "factor":39.37008},
         {"item1":"m", "item2":"cm", "factor":100},
+        {"item1":"cm", "item2":"mm", "factor":10},
         {"item1":"km", "item2":"mi", "factor":0.6213712},
         {"item1":"ft", "item2":"in", "factor":12},
         {"item1":"yd", "item2":"ft", "factor":3},