diff --git a/TODO b/TODO
index 6a264514..1e8ab5d9 100644
--- a/TODO
+++ b/TODO
@@ -97,8 +97,6 @@ Comments appear in the code prefixed by "ABI"
 * Consider having addArrayItem, replaceKey, etc. return the new value
   so you can say
   auto oh = dict.replaceKey("/Key", QPDFObjectHandle::newSomething());
-* Do something about QPDFObjectHandle::Matrix and QPDFMatrix. They
-  should be the same thing.
 
 Page splitting/merging
 ======================
diff --git a/include/qpdf/QPDFObjectHandle.hh b/include/qpdf/QPDFObjectHandle.hh
index 07c5b427..dc883102 100644
--- a/include/qpdf/QPDFObjectHandle.hh
+++ b/include/qpdf/QPDFObjectHandle.hh
@@ -267,7 +267,10 @@ class QPDFObjectHandle
         double ury;
     };
 
-    // Convenience object for transformation matrices
+    // Convenience object for transformation matrices. See also
+    // QPDFMatrix. Unfortunately we can't replace this with QPDFMatrix
+    // because QPDFMatrix's default constructor creates the identity
+    // transform matrix and this one is all zeroes.
     class Matrix
     {
       public: