diff --git a/ChangeLog b/ChangeLog
index 66966f7b..2463c250 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,9 @@
 2018-06-22  Jay Berkenbilt  <ejb@ql.org>
 
+	* Don't leave files open when merging. This makes it possible
+	merge more files at once than the operating system's open file
+	limit. Fixes #154.
+
 	* Add ClosedFileInputSource class, and input source that keeps its
 	input file closed when not reading it. At the expense of some
 	performance, this allows you to operate on many files without
diff --git a/qpdf/qpdf.cc b/qpdf/qpdf.cc
index 49271c68..783548ef 100644
--- a/qpdf/qpdf.cc
+++ b/qpdf/qpdf.cc
@@ -7,6 +7,7 @@
 
 #include <qpdf/QUtil.hh>
 #include <qpdf/QTC.hh>
+#include <qpdf/ClosedFileInputSource.hh>
 #include <qpdf/Pl_StdioFile.hh>
 #include <qpdf/Pl_Discard.hh>
 #include <qpdf/PointerHolder.hh>
@@ -2083,8 +2084,9 @@ static void handle_page_specs(QPDF& pdf, Options& o,
                 QTC::TC("qpdf", "qpdf pages encryption password");
                 password = o.encryption_file_password;
             }
-            qpdf->processFile(
-                page_spec.filename.c_str(), password);
+            qpdf->processInputSource(
+                new ClosedFileInputSource(
+                    page_spec.filename.c_str()), password);
             page_spec_qpdfs[page_spec.filename] = qpdf;
         }