diff -u mimedefang-2.78/configure mimedefang-2.78/configure
--- mimedefang-2.78/configure
+++ mimedefang-2.78/configure
@@ -4231,7 +4231,7 @@
 $as_echo_n "checking if it is safe to destroy and recreate a Perl interpreter... " >&6; }
    LIBS="-lperl $LIBS"
    LDFLAGS="$EMBPERLLDFLAGS $LDFLAGS"
-   CFLAGS="$EMBPERLCFLAGS $CFLAGS"
+   CFLAGS="$EMBPERLCFLAGS $CFLAGS $PTHREAD_FLAG"
    if test "$cross_compiling" = yes; then :
   { { $as_echo "$as_me:${as_lineno-$LINENO}: error: in \`$ac_pwd':" >&5
 $as_echo "$as_me: error: in \`$ac_pwd':" >&2;}
diff -u mimedefang-2.78/configure.in mimedefang-2.78/configure.in
--- mimedefang-2.78/configure.in
+++ mimedefang-2.78/configure.in
@@ -343,7 +343,7 @@
    AC_MSG_CHECKING([if it is safe to destroy and recreate a Perl interpreter])
    LIBS="-lperl $LIBS"
    LDFLAGS="$EMBPERLLDFLAGS $LDFLAGS"
-   CFLAGS="$EMBPERLCFLAGS $CFLAGS"
+   CFLAGS="$EMBPERLCFLAGS $CFLAGS $PTHREAD_FLAG"
    AC_TRY_RUN([
 #include <EXTERN.h>
 #include <perl.h>
diff -u mimedefang-2.78/debian/changelog mimedefang-2.78/debian/changelog
--- mimedefang-2.78/debian/changelog
+++ mimedefang-2.78/debian/changelog
@@ -1,3 +1,10 @@
+mimedefang (2.78-1ubuntu2~rlaager1) xenial; urgency=medium
+
+  * Use $PTHREAD_FLAG in the SAFE_EMBED_PERL test.  This allows, at runtime,
+    md-mx-ctrl reread (and /etc/init.d/mimedefang reread) to work.
+
+ -- Richard Laager <rlaager@wiktel.com>  Thu, 15 Sep 2016 00:02:52 -0500
+
 mimedefang (2.78-1ubuntu1) xenial; urgency=medium
 
   * Update to PHP7.0 dependencies (LP: #1562133).