diff --git a/Makefile.inc b/Makefile.inc
index 9b97adb..f163fda 100644
--- a/Makefile.inc
+++ b/Makefile.inc
@@ -19,7 +19,7 @@ libdir = $(prefix)/lib
 AR=ar
 RANLIB=ranlib
 
-CFLAGS += -g -std=c99 -pipe -Wall
+CFLAGS += -g -D_POSIX_C_SOURCE=200809L -std=c99 -pipe -Wall
 LDFLAGS += -g -lpthread -lrt -lm
 INC += -I$(ROOTDIR)/common
 
diff --git a/common/b.c b/common/b.c
index 6df833a..ee0650d 100644
--- a/common/b.c
+++ b/common/b.c
@@ -1,4 +1,3 @@
-#define _POSIX_C_SOURCE 200809L
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
@@ -31,7 +30,7 @@ static unsigned long long dt;
 static unsigned long long tic() {
 	struct timespec ts;
 
-	if (clock_gettime(CLOCK_MONOTONIC, &ts) < 0) {
+	if (clock_gettime(CLOCK_REALTIME, &ts) < 0) {
 		fprintf(stderr, "bench: clock_gettime failed: %s\n", strerror(errno));
 		return 0;
 	}
diff --git a/common/t.c b/common/t.c
index daf06fd..083e308 100644
--- a/common/t.c
+++ b/common/t.c
@@ -1,4 +1,3 @@
-#define _POSIX_C_SOURCE 200809L
 #include <stdlib.h>
 #include <stdio.h>
 #include <stdarg.h>
@@ -17,6 +16,7 @@
 static int failed;
 static const char *name;
 
+static int slow;
 static int verbose;
 static int count;
 static int nfailed;
@@ -76,7 +76,28 @@ static int summary() {
 	return !!nfailed;
 }
 
-int main() {
+static void usage() {
+	fprintf(stderr, "usage: ./t [-vs]\n");
+	exit(1);
+}
+
+int main(int argc, char *argv[]) {
+	int c;
+
+	while((c = getopt(argc, argv, "vs")) != -1)
+		switch(c) {
+		case 'v':
+			verbose = 1;
+			break;
+		case 's':
+			slow = 1; /* TODO */
+			break;
+		default:
+			usage();
+		}
+	if (optind != argc)
+		usage();
+
 #define T(t) run(#t, t);
 #include "tests.h"
 	return summary();
diff --git a/src/misc/basename.c b/src/misc/basename.c
index 33159fc..95e0d36 100644
--- a/src/misc/basename.c
+++ b/src/misc/basename.c
@@ -1,4 +1,3 @@
-#define _POSIX_C_SOURCE 200809L
 #include <stdlib.h>
 #include <string.h>
 #include <libgen.h>
diff --git a/src/misc/dirname.c b/src/misc/dirname.c
index 50538b6..b4a1c48 100644
--- a/src/misc/dirname.c
+++ b/src/misc/dirname.c
@@ -1,4 +1,3 @@
-#define _POSIX_C_SOURCE 200809L
 #include <stdlib.h>
 #include <string.h>
 #include <libgen.h>
diff --git a/src/regex/bench.c b/src/regex/bench.c
index 3f911ca..526662b 100644
--- a/src/regex/bench.c
+++ b/src/regex/bench.c
@@ -1,4 +1,3 @@
-#define _POSIX_C_SOURCE 200809L
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
diff --git a/src/stdio/bench.c b/src/stdio/bench.c
index ade4095..95f9b90 100644
--- a/src/stdio/bench.c
+++ b/src/stdio/bench.c
@@ -1,4 +1,3 @@
-#define _POSIX_C_SOURCE 200809L
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
diff --git a/src/stdio/fscanf.c b/src/stdio/fscanf.c
index d0c47c7..1de09c3 100644
--- a/src/stdio/fscanf.c
+++ b/src/stdio/fscanf.c
@@ -1,4 +1,3 @@
-#define _POSIX_C_SOURCE 200809L
 #include <stdio.h>
 #include <string.h>
 #include <errno.h>
diff --git a/src/stdio/popen.c b/src/stdio/popen.c
index a373df6..f647bf4 100644
--- a/src/stdio/popen.c
+++ b/src/stdio/popen.c
@@ -1,4 +1,3 @@
-#define _POSIX_C_SOURCE 200809L
 #include <unistd.h>
 #include <stdio.h>
 #include <errno.h>
diff --git a/src/stdio/ungetc.c b/src/stdio/ungetc.c
index 855ffaa..230b327 100644
--- a/src/stdio/ungetc.c
+++ b/src/stdio/ungetc.c
@@ -1,4 +1,3 @@
-#define _POSIX_C_SOURCE 200809L
 #include <stdio.h>
 #include <string.h>
 #include <errno.h>
diff --git a/src/thread/pthread.c b/src/thread/pthread.c
index 642f772..ce39a0b 100644
--- a/src/thread/pthread.c
+++ b/src/thread/pthread.c
@@ -1,4 +1,3 @@
-#define _POSIX_C_SOURCE 200809L
 #include <pthread.h>
 #include <stdlib.h>
 #include <unistd.h>
diff --git a/src/thread/sem.c b/src/thread/sem.c
index 5bfcdfe..8bc23e8 100644
--- a/src/thread/sem.c
+++ b/src/thread/sem.c
@@ -1,4 +1,3 @@
-#define _POSIX_C_SOURCE 200809L
 #include <pthread.h>
 #include <stdlib.h>
 #include <unistd.h>