--- a/tests/BD_Shape/Makefile.am
+++ b/tests/BD_Shape/Makefile.am
@@ -21,8 +21,6 @@
 # For the most up-to-date information see the Parma Polyhedra Library
 # site: http://bugseng.com/products/ppl/ .
 
-AUTOMAKE_OPTIONS = serial-tests
-
 if VALGRIND_TESTS_ENABLED
 
 CHECKER = \
--- a/tests/Box/Makefile.am
+++ b/tests/Box/Makefile.am
@@ -21,8 +21,6 @@
 # For the most up-to-date information see the Parma Polyhedra Library
 # site: http://bugseng.com/products/ppl/ .
 
-AUTOMAKE_OPTIONS = serial-tests
-
 if VALGRIND_TESTS_ENABLED
 
 CHECKER = \
--- a/tests/Concrete_Expression/Makefile.am
+++ b/tests/Concrete_Expression/Makefile.am
@@ -21,8 +21,6 @@
 # For the most up-to-date information see the Parma Polyhedra Library
 # site: http://bugseng.com/products/ppl/ .
 
-AUTOMAKE_OPTIONS = serial-tests
-
 if VALGRIND_TESTS_ENABLED
 
 CHECKER = \
--- a/tests/Octagonal_Shape/Makefile.am
+++ b/tests/Octagonal_Shape/Makefile.am
@@ -21,8 +21,6 @@
 # For the most up-to-date information see the Parma Polyhedra Library
 # site: http://bugseng.com/products/ppl/ .
 
-AUTOMAKE_OPTIONS = serial-tests
-
 if VALGRIND_TESTS_ENABLED
 
 CHECKER = \
