diff --git a/src/compiler.h b/src/compiler.h
index 4a69adf..5ede8b2 100644
--- a/src/compiler.h
+++ b/src/compiler.h
@@ -24,9 +24,11 @@
 #ifdef HAVE___ATTRIBUTE__
 # define noinline      __attribute__((noinline))
 # define always_inline __attribute__((always_inline))
+# define unused        __attribute__((unused))
 #else
 # define noinline
 # define always_inline
+# define unused
 #endif
 
 /* Branch prediction information for the compiler. */
diff --git a/tests/example.c b/tests/example.c
index 545f3cb..7f7d2ad 100644
--- a/tests/example.c
+++ b/tests/example.c
@@ -17,15 +17,17 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include <config.h>
+
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
 #include <errno.h>
 
+#include "../src/compiler.h"
 
-int main(int argc, char **argv) {
-    (void)argv;
 
+int main(int argc, char **argv unused) {
     fprintf(stderr, "write to stderr: %d\n", argc);
     printf("write to stdout\n");
     fflush(stdout);
diff --git a/tests/example_error.c b/tests/example_error.c
index 04eca8d..e114049 100644
--- a/tests/example_error.c
+++ b/tests/example_error.c
@@ -17,12 +17,17 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include <config.h>
+
 #define _GNU_SOURCE /* for program_invocation_name */
 #include <stdio.h>
 #include <stdlib.h>
 #include <errno.h>
 #include <error.h>
 
+#include "../src/compiler.h"
+
+
 void (*error_print_progname)(void);
 
 
@@ -31,7 +36,7 @@ static void print_prognmae(void) {
 }
 
 
-int main(int argc, char **argv) {
+int main(int argc unused, char **argv unused) {
     program_invocation_name = "./example_error";
 
     error(0, 0, "<message>");
diff --git a/tests/example_exec.c b/tests/example_exec.c
index 3a18567..bd12b5a 100644
--- a/tests/example_exec.c
+++ b/tests/example_exec.c
@@ -17,11 +17,15 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include <config.h>
+
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
 
+#include "../src/compiler.h"
+
 
 #define MAGIC "@RUN_"
 #define MAGIC_LENGTH (strlen(MAGIC))
@@ -75,7 +79,7 @@ static void dump(char *argv[]) {
 }
 
 
-int main(int argc, char **argv) {
+int main(int argc unused, char **argv) {
     char argv0[strlen(argv[0]) + MAGIC_LENGTH + 3 + 1];
 
     char *old_ldpreload = getenv("LD_PRELOAD");
diff --git a/tests/example_vfork.c b/tests/example_vfork.c
index ed94e56..8c4aec9 100644
--- a/tests/example_vfork.c
+++ b/tests/example_vfork.c
@@ -17,12 +17,17 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include <config.h>
+
 #include <stdio.h>
 #include <stdlib.h>
 #include <sys/types.h>
 #include <unistd.h>
 
-int main(int argc, char **argv) {
+#include "../src/compiler.h"
+
+
+int main(int argc unused, char **argv unused) {
     pid_t pid;
 
     fprintf(stderr, "Before vfork().\n");