diff --git a/configure.in b/configure.in
index ce09a02d1..c65fa5e94 100644
--- a/configure.in
+++ b/configure.in
@@ -634,6 +634,7 @@ fi
 if test x$tss = xtrousers; then
 	AC_HAVE_LIBRARY([tspi],[LIBS="$LIBS"],[AC_MSG_ERROR([TrouSerS library libtspi not found])])
 	AC_CHECK_HEADER([trousers/tss.h],,[AC_MSG_ERROR([TrouSerS header trousers/tss.h not found!])])
+	AC_DEFINE([TSS_TROUSERS], [], [use TrouSerS library libtspi as TSS implementation])
 fi
 
 if test x$dumm = xtrue; then
diff --git a/src/libpts/Makefile.am b/src/libpts/Makefile.am
index a36e346c3..edf3f7416 100644
--- a/src/libpts/Makefile.am
+++ b/src/libpts/Makefile.am
@@ -7,7 +7,6 @@ libpts_la_LIBADD = $(top_builddir)/src/libimcv/libimcv.la
 
 if USE_TROUSERS
   libpts_la_LIBADD += -ltspi
-  AM_CFLAGS = -DTSS_TROUSERS
 endif
 
 libpts_la_SOURCES = \