diff --git a/README.maintainer b/README.maintainer
index f4021f3d..e6027447 100644
--- a/README.maintainer
+++ b/README.maintainer
@@ -21,34 +21,19 @@ Release Reminders
       LDFLAGS="-fsanitize=address" \
       --enable-werror --disable-shared
 
- * Consider running tests with latest gcc and/or valgrind.  To do
-   this, replace, build with debugging and without shared libraries.
-   In build, create z and move each executable into z.  Then create a
-   script called exec-z that contains:
+   As of gcc 6.3.0, this exposes some good things but appears to also
+   have some false positive leak reports. Valgrind is more reliable
+   but also may miss some things that this catches.
 
-   #!/bin/sh
-   exec valgrind --suppressions=/tmp/a.supp -q \
-      `dirname $0`/z/`basename $0` ${1+"$@"}
+ * Consider running tests with latest gcc and/or valgrind. To test
+   with valgrind:
 
-   Symlink exec-z to each executable.  /tmp/a.supp can be populated
-   with suppressions for libraries, for example:
+   ./configure --disable-shared
+   make -j8 -k VALGRIND=1
+   make -k check NO_REBUILD=1
 
-   {
-      zlib1
-      Memcheck:Cond
-      fun:inflateReset2
-      fun:inflateInit2_
-   }
-   {
-      index
-      Memcheck:Cond
-      fun:index
-      fun:expand_dynamic_string_token
-      fun:_dl_map_object
-      fun:map_doit
-   }
-
-   You can generate these by running valgrind with --gen-suppressions=yes.
+   This moves each binary into a subdirectory and replaces it with a
+   link to make/exec-z. See make/exec-z.
 
  * Check all open issues in the sourceforge trackers and on github.
 
diff --git a/libqpdf/Pl_DCT.cc b/libqpdf/Pl_DCT.cc
index 68cdc973..121ee273 100644
--- a/libqpdf/Pl_DCT.cc
+++ b/libqpdf/Pl_DCT.cc
@@ -107,6 +107,25 @@ Pl_DCT::finish()
     }
 }
 
+class Freer
+{
+  public:
+    Freer(unsigned char** p) :
+        p(p)
+    {
+    }
+    ~Freer()
+    {
+        if (*p)
+        {
+            free(*p);
+        }
+    }
+
+  private:
+    unsigned char** p;
+};
+
 void
 Pl_DCT::compress(void* cinfo_p, PointerHolder<Buffer> b)
 {
@@ -124,6 +143,7 @@ Pl_DCT::compress(void* cinfo_p, PointerHolder<Buffer> b)
 #       pragma GCC diagnostic pop
 #endif
     unsigned char* outbuffer = 0;
+    Freer freer(&outbuffer);
     unsigned long outsize = 0;
     jpeg_mem_dest(cinfo, &outbuffer, &outsize);
 
@@ -160,8 +180,6 @@ Pl_DCT::compress(void* cinfo_p, PointerHolder<Buffer> b)
     jpeg_finish_compress(cinfo);
     this->getNext()->write(outbuffer, outsize);
     this->getNext()->finish();
-
-    free(outbuffer);
 }
 
 void
diff --git a/make/exec-z b/make/exec-z
new file mode 100755
index 00000000..dc21dbc1
--- /dev/null
+++ b/make/exec-z
@@ -0,0 +1,24 @@
+#!/bin/sh
+# This script is used for valgrind testing. See README.maintainer.
+
+# Create a suppressions file. This can be updated by running valgrind
+# with --gen-suppressions=yes.
+test -f /tmp/a.supp || cat > /tmp/a.supp <<EOF
+{
+   zlib1
+   Memcheck:Cond
+   fun:inflateReset2
+   fun:inflateInit2_
+}
+{
+   index
+   Memcheck:Cond
+   fun:index
+   fun:expand_dynamic_string_token
+   fun:_dl_map_object
+   fun:map_doit
+}
+EOF
+
+exec valgrind --suppressions=/tmp/a.supp -q \
+   `dirname $0`/z/`basename $0` ${1+"$@"}
diff --git a/make/libtool.mk b/make/libtool.mk
index c6cf4e4d..c3af7b9f 100644
--- a/make/libtool.mk
+++ b/make/libtool.mk
@@ -102,6 +102,7 @@ endef
 # Usage: $(call makebin,objs,binary,ldflags,libs)
 define makebin
 	$(LIBTOOL) --mode=link $(CXX) $(CXXFLAGS) $(1) -o $(2) $(4) $(3)
+	if [ "$(VALGRIND)" = 1 ]; then make/valgrind-wrap $(2); fi
 endef
 
 # Install target
diff --git a/make/valgrind-wrap b/make/valgrind-wrap
new file mode 100755
index 00000000..40785bf1
--- /dev/null
+++ b/make/valgrind-wrap
@@ -0,0 +1,10 @@
+#!/bin/sh
+set -e
+pwd
+dir=$(dirname $1)
+if [ ! -x $dir/exec-z ]; then
+    ln -f make/exec-z $dir/exec-z
+fi
+mkdir -p $dir/z
+mv $1 $dir/z
+ln -f $dir/exec-z $1