diff --git a/Makefile.am b/Makefile.am
index cccad6c5ed..163b650bb0 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -51,14 +51,14 @@ AM_ETAGSFLAGS=--regex='{c}/MOCK_IMPL([^,]+,\W*\([a-zA-Z0-9_]+\)\W*,/\1/s'
 if COVERAGE_ENABLED
 TEST_CFLAGS=-fno-inline -fprofile-arcs -ftest-coverage
 if DISABLE_ASSERTS_IN_UNIT_TESTS
-TEST_CPPFLAGS=-DTOR_UNIT_TESTS -DTOR_COVERAGE -DDISABLE_ASSERTS_IN_UNIT_TESTS
+TEST_CPPFLAGS=-DTOR_UNIT_TESTS -DTOR_COVERAGE -DDISABLE_ASSERTS_IN_UNIT_TESTS @TOR_MODULES_ALL_ENABLED@
 else
-TEST_CPPFLAGS=-DTOR_UNIT_TESTS -DTOR_COVERAGE
+TEST_CPPFLAGS=-DTOR_UNIT_TESTS -DTOR_COVERAGE @TOR_MODULES_ALL_ENABLED@
 endif
 TEST_NETWORK_FLAGS=--coverage --hs-multi-client 1
 else
 TEST_CFLAGS=
-TEST_CPPFLAGS=-DTOR_UNIT_TESTS
+TEST_CPPFLAGS=-DTOR_UNIT_TESTS @TOR_MODULES_ALL_ENABLED@
 TEST_NETWORK_FLAGS=--hs-multi-client 1
 endif
 TEST_NETWORK_WARNING_FLAGS=--quiet --only-warnings
diff --git a/configure.ac b/configure.ac
index b423ea95e5..ae2c420557 100644
--- a/configure.ac
+++ b/configure.ac
@@ -234,6 +234,9 @@ dnl ---
 dnl Tor modules options. These options are namespaced with --disable-module-XXX
 dnl ---
 
+dnl All our modules.
+m4_define(MODULES, dirauth)
+
 dnl Directory Authority module.
 AC_ARG_ENABLE([module-dirauth],
               AS_HELP_STRING([--disable-module-dirauth],
@@ -243,6 +246,15 @@ AC_ARG_ENABLE([module-dirauth],
                         [Compile with Directory Authority feature support]))
 AM_CONDITIONAL(BUILD_MODULE_DIRAUTH, [test "x$enable_module_dirauth" != "xno"])
 
+dnl Helper variables.
+TOR_MODULES_ALL_ENABLED=
+AC_DEFUN([ADD_MODULE], [
+    MODULE=m4_toupper($1)
+    TOR_MODULES_ALL_ENABLED="${TOR_MODULES_ALL_ENABLED} -DHAVE_MODULE_${MODULE}=1"
+])
+m4_foreach_w([module], MODULES, [ADD_MODULE([module])])
+AC_SUBST(TOR_MODULES_ALL_ENABLED)
+
 dnl check for the correct "ar" when cross-compiling.
 dnl   (AM_PROG_AR was new in automake 1.11.2, which we do not yet require,
 dnl    so kludge up a replacement for the case where it isn't there yet.)
diff --git a/src/or/include.am b/src/or/include.am
index 93f405d619..bb505937ac 100644
--- a/src/or/include.am
+++ b/src/or/include.am
@@ -114,20 +114,23 @@ LIBTOR_A_SOURCES = \
 
 #
 # Modules are conditionnally compiled in tor starting here. We add the C files
-# only if the modules has been enabled at configure time.
+# only if the modules has been enabled at configure time. We always add the
+# source files of every module to libtor-testing.a so we can build the unit
+# tests for everything.
 #
 
 # The Directory Authority module.
-if BUILD_MODULE_DIRAUTH
-LIBTOR_A_SOURCES += \
+MODULE_DIRAUTH_SOURCES = \
 	src/or/dirauth/dircollate.c				\
 	src/or/dirauth/dirvote.c				\
 	src/or/dirauth/shared_random.c				\
 	src/or/dirauth/shared_random_state.c
+if BUILD_MODULE_DIRAUTH
+LIBTOR_A_SOURCES += $(MODULE_DIRAUTH_SOURCES)
 endif
 
 src_or_libtor_a_SOURCES = $(LIBTOR_A_SOURCES)
-src_or_libtor_testing_a_SOURCES = $(LIBTOR_A_SOURCES)
+src_or_libtor_testing_a_SOURCES = $(LIBTOR_A_SOURCES) $(MODULE_DIRAUTH_SOURCES)
 
 src_or_tor_SOURCES = src/or/tor_main.c
 AM_CPPFLAGS += -I$(srcdir)/src/or -Isrc/or