diff --git a/missing.h b/missing.h
index bc708cb..35eaf15 100644
--- a/missing.h
+++ b/missing.h
@@ -97,6 +97,58 @@ struct compat_ptp_clock_caps {
 
 #endif /*LINUX_VERSION_CODE < 5.8*/
 
+#ifndef PTP_MAX_SAMPLES
+#define PTP_MAX_SAMPLES 25 /* Maximum allowed offset measurement samples. */
+#endif /* PTP_MAX_SAMPLES */
+
+#ifndef PTP_SYS_OFFSET
+
+#define PTP_SYS_OFFSET     _IOW(PTP_CLK_MAGIC, 5, struct ptp_sys_offset)
+
+struct ptp_sys_offset {
+	unsigned int n_samples; /* Desired number of measurements. */
+	unsigned int rsv[3];    /* Reserved for future use. */
+	/*
+	 * Array of interleaved system/phc time stamps. The kernel
+	 * will provide 2*n_samples + 1 time stamps, with the last
+	 * one as a system time stamp.
+	 */
+	struct ptp_clock_time ts[2 * PTP_MAX_SAMPLES + 1];
+};
+
+#endif /* PTP_SYS_OFFSET */
+
+#ifndef PTP_SYS_OFFSET_PRECISE
+
+#define PTP_SYS_OFFSET_PRECISE \
+	_IOWR(PTP_CLK_MAGIC, 8, struct ptp_sys_offset_precise)
+
+struct ptp_sys_offset_precise {
+	struct ptp_clock_time device;
+	struct ptp_clock_time sys_realtime;
+	struct ptp_clock_time sys_monoraw;
+	unsigned int rsv[4];    /* Reserved for future use. */
+};
+
+#endif /* PTP_SYS_OFFSET_PRECISE */
+
+#ifndef PTP_SYS_OFFSET_EXTENDED
+
+#define PTP_SYS_OFFSET_EXTENDED \
+	_IOWR(PTP_CLK_MAGIC, 9, struct ptp_sys_offset_extended)
+
+struct ptp_sys_offset_extended {
+	unsigned int n_samples; /* Desired number of measurements. */
+	unsigned int rsv[3];    /* Reserved for future use. */
+	/*
+	 * Array of [system, phc, system] time stamps. The kernel will provide
+	 * 3*n_samples time stamps.
+	 */
+	struct ptp_clock_time ts[PTP_MAX_SAMPLES][3];
+};
+
+#endif /* PTP_SYS_OFFSET_EXTENDED */
+
 #ifndef PTP_PIN_SETFUNC
 
 enum ptp_pin_function {
diff --git a/sysoff.c b/sysoff.c
index ec77a0d..2743859 100644
--- a/sysoff.c
+++ b/sysoff.c
@@ -27,8 +27,6 @@
 
 #define NS_PER_SEC 1000000000LL
 
-#ifdef PTP_SYS_OFFSET
-
 static int64_t pctns(struct ptp_clock_time *t)
 {
 	return t->sec * NS_PER_SEC + t->nsec;
@@ -36,7 +34,6 @@ static int64_t pctns(struct ptp_clock_time *t)
 
 static int sysoff_precise(int fd, int64_t *result, uint64_t *ts)
 {
-#ifdef PTP_SYS_OFFSET_PRECISE
 	struct ptp_sys_offset_precise pso;
 	memset(&pso, 0, sizeof(pso));
 	if (ioctl(fd, PTP_SYS_OFFSET_PRECISE, &pso)) {
@@ -46,9 +43,6 @@ static int sysoff_precise(int fd, int64_t *result, uint64_t *ts)
 	*result = pctns(&pso.sys_realtime) - pctns(&pso.device);
 	*ts = pctns(&pso.sys_realtime);
 	return SYSOFF_PRECISE;
-#else
-	return SYSOFF_COMPILE_TIME_MISSING;
-#endif
 }
 
 static int64_t sysoff_estimate(struct ptp_clock_time *pct, int extended,
@@ -99,7 +93,6 @@ static int64_t sysoff_estimate(struct ptp_clock_time *pct, int extended,
 static int sysoff_extended(int fd, int n_samples,
 			   int64_t *result, uint64_t *ts, int64_t *delay)
 {
-#ifdef PTP_SYS_OFFSET_EXTENDED
 	struct ptp_sys_offset_extended pso;
 	memset(&pso, 0, sizeof(pso));
 	pso.n_samples = n_samples;
@@ -109,9 +102,6 @@ static int sysoff_extended(int fd, int n_samples,
 	}
 	*result = sysoff_estimate(&pso.ts[0][0], 1, n_samples, ts, delay);
 	return SYSOFF_EXTENDED;
-#else
-	return SYSOFF_COMPILE_TIME_MISSING;
-#endif
 }
 
 static int sysoff_basic(int fd, int n_samples,
@@ -140,7 +130,7 @@ int sysoff_measure(int fd, int method, int n_samples,
 	case SYSOFF_BASIC:
 		return sysoff_basic(fd, n_samples, result, ts, delay);
 	}
-	return SYSOFF_COMPILE_TIME_MISSING;
+	return SYSOFF_RUN_TIME_MISSING;
 }
 
 int sysoff_probe(int fd, int n_samples)
@@ -164,18 +154,3 @@ int sysoff_probe(int fd, int n_samples)
 
 	return SYSOFF_RUN_TIME_MISSING;
 }
-
-#else /* !PTP_SYS_OFFSET */
-
-int sysoff_measure(int fd, int method, int n_samples,
-		   int64_t *result, uint64_t *ts, int64_t *delay)
-{
-	return SYSOFF_COMPILE_TIME_MISSING;
-}
-
-int sysoff_probe(int fd, int n_samples)
-{
-	return SYSOFF_COMPILE_TIME_MISSING;
-}
-
-#endif /* PTP_SYS_OFFSET */
diff --git a/sysoff.h b/sysoff.h
index 79d2290..e4de919 100644
--- a/sysoff.h
+++ b/sysoff.h
@@ -19,9 +19,9 @@
  */
 
 #include <stdint.h>
+#include "missing.h"
 
 enum {
-	SYSOFF_COMPILE_TIME_MISSING = -2,
 	SYSOFF_RUN_TIME_MISSING = -1,
 	SYSOFF_PRECISE,
 	SYSOFF_EXTENDED,