diff --git a/configure.ac b/configure.ac
index 91500087..95d795c3 100644
--- a/configure.ac
+++ b/configure.ac
@@ -54,9 +54,22 @@ m4_define([serial_tests], [
                 awk '{split ($NF,a,"."); if (a[1] == 1 && a[2] >= 12) { print "serial-tests" }}'
     ])
 ])
+
+dnl Automake 1.14+ warns if sources are in sub-directories but subdir-objects
+dnl options is not enabled. However, automake before 1.15a has a bug that causes
+dnl variable expansion to fail in foo_SOURCES when this option is used.
+dnl As most of our build systems are now likely to use automake 1.16+ add a
+dnl work around to conditionally add subdir-objects option.
+m4_define([subdir_objects], [
+    m4_esyscmd([automake --version |
+                head -1 |
+                awk '{split ($NF,a,"."); if (a[1] == 1 && a[2] >= 16) { print "subdir-objects" }}'
+    ])
+])
+
 # This foreign option prevents autoreconf from overriding our COPYING and
 # INSTALL targets:
-AM_INIT_AUTOMAKE(foreign serial_tests 1.9) dnl NB: Do not [quote] this parameter.
+AM_INIT_AUTOMAKE(foreign serial_tests subdir_objects 1.9) dnl NB: Do not [quote] this parameter.
 AC_CANONICAL_HOST
 AC_USE_SYSTEM_EXTENSIONS