diff --git a/ChangeLog b/ChangeLog
index 35b78e91..0c43cd83 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2012-07-15  Jay Berkenbilt  <ejb@ql.org>
+
+	* libqpdf/QPDFWriter.cc (copyEncryptionParameters): Bug fix: qpdf
+	was not preserving whether or not AES encryption was being used
+	when copying encryption parameters.
+
 2012-07-14  Jay Berkenbilt  <ejb@ql.org>
 
 	* QPDFWriter: add public copyEncryptionParameters to allow copying
diff --git a/libqpdf/QPDFWriter.cc b/libqpdf/QPDFWriter.cc
index 96f3ff21..b5daab23 100644
--- a/libqpdf/QPDFWriter.cc
+++ b/libqpdf/QPDFWriter.cc
@@ -409,10 +409,34 @@ QPDFWriter::copyEncryptionParameters(QPDF& qpdf)
 	    this->encrypt_metadata =
 		encrypt.getKey("/EncryptMetadata").getBoolValue();
 	}
+        if (V >= 4)
+        {
+            if (encrypt.hasKey("/CF") &&
+                encrypt.getKey("/CF").isDictionary() &&
+                encrypt.hasKey("/StmF") &&
+                encrypt.getKey("/StmF").isName())
+            {
+                // Determine whether to use AES from StmF.  QPDFWriter
+                // can't write files with different StrF and StmF.
+                QPDFObjectHandle CF = encrypt.getKey("/CF");
+                QPDFObjectHandle StmF = encrypt.getKey("/StmF");
+                if (CF.hasKey(StmF.getName()) &&
+                    CF.getKey(StmF.getName()).isDictionary())
+                {
+                    QPDFObjectHandle StmF_data = CF.getKey(StmF.getName());
+                    if (StmF_data.hasKey("/CFM") &&
+                        StmF_data.getKey("/CFM").isName() &&
+                        StmF_data.getKey("/CFM").getName() == "/AESV2")
+                    {
+                        this->encrypt_use_aes = true;
+                    }
+                }
+            }
+        }
 	QTC::TC("qpdf", "QPDFWriter copy encrypt metadata",
 		this->encrypt_metadata ? 0 : 1);
-        this->id1 =
-            trailer.getKey("/ID").getArrayItem(0).getStringValue();
+        QTC::TC("qpdf", "QPDFWriter copy use_aes",
+                this->encrypt_use_aes ? 0 : 1);
 	setEncryptionParametersInternal(
 	    V,
 	    encrypt.getKey("/R").getIntValue(),
diff --git a/qpdf/qpdf.testcov b/qpdf/qpdf.testcov
index a570f642..c51e527b 100644
--- a/qpdf/qpdf.testcov
+++ b/qpdf/qpdf.testcov
@@ -234,3 +234,4 @@ QPDF replace foreign indirect with null 0
 QPDF not copying pages object 0
 QPDF insert foreign page 0
 QPDFWriter foreign object 0
+QPDFWriter copy use_aes 1