diff --git a/include/common/compat.h b/include/common/compat.h
index d43b89d..35782de 100644
--- a/include/common/compat.h
+++ b/include/common/compat.h
@@ -99,7 +99,7 @@
 #endif
 
 /* systems without such defines do not know clockid_t */
-#if !defined(_POSIX_TIMERS) || (_POSIX_C_SOURCE < 199309L)
+#if !(_POSIX_TIMERS > 0) || (_POSIX_C_SOURCE < 199309L)
 #define clockid_t int
 #undef CLOCK_REALTIME
 #undef CLOCK_MONOTONIC
diff --git a/include/common/time.h b/include/common/time.h
index 9920a77..2633b1c 100644
--- a/include/common/time.h
+++ b/include/common/time.h
@@ -519,7 +519,7 @@
 /* returns the system's monotonic time in nanoseconds if supported, otherwise zero */
 static inline uint64_t now_mono_time()
 {
-#if defined(_POSIX_TIMERS) && defined(_POSIX_MONOTONIC_CLOCK)
+#if (_POSIX_TIMERS > 0) && defined(_POSIX_MONOTONIC_CLOCK)
 	struct timespec ts;
 	clock_gettime(CLOCK_MONOTONIC, &ts);
 	return ts.tv_sec * 1000000000ULL + ts.tv_nsec;
@@ -531,7 +531,7 @@
 /* returns the current thread's cumulated CPU time in nanoseconds if supported, otherwise zero */
 static inline uint64_t now_cpu_time()
 {
-#if defined(_POSIX_TIMERS) && defined(_POSIX_THREAD_CPUTIME)
+#if (_POSIX_TIMERS > 0) && defined(_POSIX_THREAD_CPUTIME)
 	struct timespec ts;
 	clock_gettime(CLOCK_THREAD_CPUTIME_ID, &ts);
 	return ts.tv_sec * 1000000000ULL + ts.tv_nsec;
@@ -543,7 +543,7 @@
 /* returns another thread's cumulated CPU time in nanoseconds if supported, otherwise zero */
 static inline uint64_t now_cpu_time_thread(const struct thread_info *thr)
 {
-#if defined(_POSIX_TIMERS) && defined(_POSIX_THREAD_CPUTIME)
+#if (_POSIX_TIMERS > 0) && defined(_POSIX_THREAD_CPUTIME)
 	struct timespec ts;
 	clock_gettime(thr->clock_id, &ts);
 	return ts.tv_sec * 1000000000ULL + ts.tv_nsec;