diff --git a/Makefile.in b/Makefile.in
index ba31c2efd0c..f0803ca2a5c 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -1,5 +1,5 @@
 all:
-	$(MAKE) omc @OMLIBRARY_TARGET@
+	$(MAKE) omc @OMLIBRARY_TARGET@ omc-diff
 	$(MAKE) omplot
 	$(MAKE) omedit omoptim
 
@@ -17,6 +17,8 @@ omedit:
 	$(MAKE) -C OMEdit
 omoptim:
 	$(MAKE) -C OMOptim
+omc-diff:
+	$(MAKE) -C testsuite/difftool "OMBUILDDIR=@OMBUILDDIR@" CC="@CC@" CFLAGS="@CFLAGS@"
 
 clean:
 	test ! -d build || rm -r build/
diff --git a/configure.ac b/configure.ac
index 01f021089a5..ccd41141eb8 100644
--- a/configure.ac
+++ b/configure.ac
@@ -3,6 +3,9 @@ dnl Process this file with autoconf to produce a configure script.
 AC_PREREQ([2.63])
 AC_INIT([OpenModelica],[dev],[https://trac.openmodelica.org/OpenModelica],[openmodelica],[https://openmodelica.org])
 
+AC_LANG([C])
+AC_PROG_CC
+
 m4_include([common/m4/pre-commit.m4])
 m4_include([common/m4/ombuilddir.m4])
 cp common/install-sh common/config.guess common/config.sub ./
diff --git a/testsuite b/testsuite
index 3d07c1eeb7e..77d2e588485 160000
--- a/testsuite
+++ b/testsuite
@@ -1 +1 @@
-Subproject commit 3d07c1eeb7e17350fd04804a1d49a32c05bc1538
+Subproject commit 77d2e58848584c0d09af5cd5202dd06b4ed509d2