diff --git a/ChangeLog b/ChangeLog
index 41c4671b..95ed40c7 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2022-05-17  Jay Berkenbilt  <ejb@ql.org>
+
+        * Allow passing *uninitialized* (not null) objects to
+        replaceStreamData as filter and/or decode_parms to leave any
+        existing values for /Filter and /DecodeParms untouched.
+
 2022-05-15  Jay Berkenbilt  <ejb@ql.org>
 
         * Add QUtil::is_long_long to test whether a string can be
diff --git a/include/qpdf/QPDFObjectHandle.hh b/include/qpdf/QPDFObjectHandle.hh
index 2265459d..557330e5 100644
--- a/include/qpdf/QPDFObjectHandle.hh
+++ b/include/qpdf/QPDFObjectHandle.hh
@@ -1199,13 +1199,21 @@ class QPDFObjectHandle
     QPDF_DLL
     void replaceDict(QPDFObjectHandle const&);
 
-    // Replace this stream's stream data with the given data buffer,
-    // and replace the /Filter and /DecodeParms keys in the stream
-    // dictionary with the given values.  (If either value is empty,
-    // the corresponding key is removed.)  The stream's /Length key is
-    // replaced with the length of the data buffer.  The stream is
-    // interpreted as if the data read from the file, after any
-    // decryption filters have been applied, is as presented.
+    // REPLACING STREAM DATA
+
+    // Note about all replaceStreamData methods: whatever values are
+    // passed as filter and decode_parms will overwrite /Filter and
+    // /DecodeParms in the stream. Passing a null object
+    // (QPDFObjectHandle::newNull()) will remove those values from the
+    // stream dictionary. From qpdf 11, passing an *uninitialized*
+    // QPDFObjectHandle (QPDFObjectHandle()) will leave any existing
+    // values untouched.
+
+    // Replace this stream's stream data with the given data buffer.
+    // The stream's /Length key is replaced with the length of the
+    // data buffer. The stream is interpreted as if the data read from
+    // the file, after any decryption filters have been applied, is as
+    // presented.
     QPDF_DLL
     void replaceStreamData(
         std::shared_ptr<Buffer> data,
diff --git a/libqpdf/QPDF_Stream.cc b/libqpdf/QPDF_Stream.cc
index c6f0d873..11dbe7e3 100644
--- a/libqpdf/QPDF_Stream.cc
+++ b/libqpdf/QPDF_Stream.cc
@@ -725,8 +725,12 @@ QPDF_Stream::replaceFilterData(
     QPDFObjectHandle const& decode_parms,
     size_t length)
 {
-    this->stream_dict.replaceKey("/Filter", filter);
-    this->stream_dict.replaceKey("/DecodeParms", decode_parms);
+    if (filter.isInitialized()) {
+        this->stream_dict.replaceKey("/Filter", filter);
+    }
+    if (decode_parms.isInitialized()) {
+        this->stream_dict.replaceKey("/DecodeParms", decode_parms);
+    }
     if (length == 0) {
         QTC::TC("qpdf", "QPDF_Stream unknown stream length");
         this->stream_dict.removeKey("/Length");