diff --git a/conf/confbase.Y b/conf/confbase.Y
index 390041c4..16330984 100644
--- a/conf/confbase.Y
+++ b/conf/confbase.Y
@@ -80,8 +80,7 @@ CF_DECLS
 %type <iface> ipa_scope
 
 %type <i> expr bool pxlen4
-%type <i32> expr_us
-%type <time> time
+%type <time> expr_us time
 %type <a> ipa
 %type <net> net_ip4_ net_ip6_ net_ip6 net_ip_ net_ip net_or_ipa
 %type <net_ptr> net_ net_any net_vpn4_ net_vpn6_ net_vpn_ net_roa4_ net_roa6_ net_roa_
@@ -137,9 +136,9 @@ expr:
 
 
 expr_us:
-   expr S  { $$ = (u32) $1 * 1000000; }
- | expr MS { $$ = (u32) $1 * 1000; }
- | expr US { $$ = (u32) $1 * 1; }
+   expr S  { $$ = $1 S_; }
+ | expr MS { $$ = $1 MS_; }
+ | expr US { $$ = $1 US_; }
  ;
 
 /* Switches */
diff --git a/lib/birdlib.h b/lib/birdlib.h
index a0826aab..9a77fc7b 100644
--- a/lib/birdlib.h
+++ b/lib/birdlib.h
@@ -71,9 +71,9 @@ static inline int u64_cmp(u64 i1, u64 i2)
 typedef s64 btime;
 typedef s64 bird_clock_t;
 
-#define S_	*1000000
-#define MS_	*1000
-#define US_	*1
+#define S_	* (btime) 1000000
+#define MS_	* (btime) 1000
+#define US_	* (btime) 1
 #define TO_S	/1000000
 #define TO_MS	/1000
 #define TO_US	/1
@@ -82,6 +82,7 @@ typedef s64 bird_clock_t;
 #define S	S_
 #define MS	MS_
 #define US	US_
+#define NS	/1000
 #endif
 
 
diff --git a/nest/password.c b/nest/password.c
index 72f23f5d..6f87af21 100644
--- a/nest/password.c
+++ b/nest/password.c
@@ -10,6 +10,7 @@
 #include "nest/bird.h"
 #include "nest/password.h"
 #include "lib/string.h"
+#include "lib/timer.h"
 #include "lib/mac.h"
 
 struct password_item *last_password_item = NULL;
diff --git a/proto/radv/radv.c b/proto/radv/radv.c
index 978d2091..415cd1d9 100644
--- a/proto/radv/radv.c
+++ b/proto/radv/radv.c
@@ -55,8 +55,8 @@ radv_timer(timer *tm)
 
   /* Update timer */
   ifa->last = current_time();
-  btime t = (btime) ifa->cf->min_ra_int S;
-  btime r = (btime) (ifa->cf->max_ra_int - ifa->cf->min_ra_int) S;
+  btime t = ifa->cf->min_ra_int S;
+  btime r = (ifa->cf->max_ra_int - ifa->cf->min_ra_int) S;
   t += random() % (r + 1);
 
   if (ifa->initial)
@@ -93,7 +93,7 @@ radv_iface_notify(struct radv_iface *ifa, int event)
   }
 
   /* Update timer */
-  btime t = ifa->last + (btime) ifa->cf->min_delay S - current_time();
+  btime t = ifa->last + ifa->cf->min_delay S - current_time();
   tm2_start(ifa->timer, t);
 }
 
diff --git a/proto/rip/config.Y b/proto/rip/config.Y
index ba9ac20b..e3bc4ae3 100644
--- a/proto/rip/config.Y
+++ b/proto/rip/config.Y
@@ -147,9 +147,9 @@ rip_iface_item:
  | SPLIT HORIZON bool	{ RIP_IFACE->split_horizon = $3; }
  | POISON REVERSE bool	{ RIP_IFACE->poison_reverse = $3; }
  | CHECK ZERO bool	{ RIP_IFACE->check_zero = $3; }
- | UPDATE TIME expr	{ RIP_IFACE->update_time = (btime) $3 S_; if ($3<=0) cf_error("Update time must be positive"); }
- | TIMEOUT TIME expr	{ RIP_IFACE->timeout_time = (btime) $3 S_; if ($3<=0) cf_error("Timeout time must be positive"); }
- | GARBAGE TIME expr	{ RIP_IFACE->garbage_time = (btime) $3 S_; if ($3<=0) cf_error("Garbage time must be positive"); }
+ | UPDATE TIME expr	{ RIP_IFACE->update_time = $3 S_; if ($3<=0) cf_error("Update time must be positive"); }
+ | TIMEOUT TIME expr	{ RIP_IFACE->timeout_time = $3 S_; if ($3<=0) cf_error("Timeout time must be positive"); }
+ | GARBAGE TIME expr	{ RIP_IFACE->garbage_time = $3 S_; if ($3<=0) cf_error("Garbage time must be positive"); }
  | ECMP WEIGHT expr	{ RIP_IFACE->ecmp_weight = $3 - 1; if (($3<1) || ($3>256)) cf_error("ECMP weight must be in range 1-256"); }
  | RX BUFFER expr	{ RIP_IFACE->rx_buffer = $3; if (($3<256) || ($3>65535)) cf_error("RX length must be in range 256-65535"); }
  | TX LENGTH expr	{ RIP_IFACE->tx_length = $3; if (($3<256) || ($3>65535)) cf_error("TX length must be in range 256-65535"); }
diff --git a/proto/rpki/rpki.c b/proto/rpki/rpki.c
index cddbf017..f17024fe 100644
--- a/proto/rpki/rpki.c
+++ b/proto/rpki/rpki.c
@@ -318,7 +318,7 @@ rpki_cache_change_state(struct rpki_cache *cache, const enum rpki_cache_state ne
 static void
 rpki_schedule_next_refresh(struct rpki_cache *cache)
 {
-  btime t = (btime) cache->refresh_interval S;
+  btime t = cache->refresh_interval S;
 
   CACHE_DBG(cache, "after %t s", t);
   tm2_start(cache->refresh_timer, t);
@@ -327,7 +327,7 @@ rpki_schedule_next_refresh(struct rpki_cache *cache)
 static void
 rpki_schedule_next_retry(struct rpki_cache *cache)
 {
-  btime t = (btime) cache->retry_interval S;
+  btime t = cache->retry_interval S;
 
   CACHE_DBG(cache, "after %t s", t);
   tm2_start(cache->retry_timer, t);
@@ -337,7 +337,7 @@ static void
 rpki_schedule_next_expire_check(struct rpki_cache *cache)
 {
   /* A minimum time to wait is 1 second */
-  btime t = cache->last_update + (btime) cache->expire_interval S - current_time();
+  btime t = cache->last_update + cache->expire_interval S - current_time();
   t = MAX(t, 1 S);
 
   CACHE_DBG(cache, "after %t s", t);
@@ -483,7 +483,7 @@ rpki_expire_hook(timer *tm)
 
   CACHE_DBG(cache, "%s", rpki_cache_state_to_str(cache->state));
 
-  btime t = cache->last_update + (btime) cache->expire_interval S - current_time();
+  btime t = cache->last_update + cache->expire_interval S - current_time();
   if (t <= 0)
   {
     CACHE_TRACE(D_EVENTS, cache, "All ROAs expired");
diff --git a/sysdep/unix/io.c b/sysdep/unix/io.c
index 99f52aa9..25121d74 100644
--- a/sysdep/unix/io.c
+++ b/sysdep/unix/io.c
@@ -406,7 +406,7 @@ times_init(struct timeloop *loop)
   if ((ts.tv_sec < 0) || (((s64) ts.tv_sec) > ((s64) 1 << 40)))
     log(L_WARN "Monotonic clock is crazy");
 
-  loop->last_time = ((s64) ts.tv_sec S) + (ts.tv_nsec / 1000);
+  loop->last_time = ts.tv_sec S + ts.tv_nsec NS;
   loop->real_time = 0;
 }
 
@@ -420,7 +420,7 @@ times_update(struct timeloop *loop)
   if (rv < 0)
     die("clock_gettime: %m");
 
-  btime new_time = ((s64) ts.tv_sec S) + (ts.tv_nsec / 1000);
+  btime new_time = ts.tv_sec S + ts.tv_nsec NS;
 
   if (new_time < loop->last_time)
     log(L_ERR "Monotonic clock is broken");
@@ -439,7 +439,7 @@ times_update_real_time(struct timeloop *loop)
   if (rv < 0)
     die("clock_gettime: %m");
 
-  loop->real_time = ((s64) ts.tv_sec S) + (ts.tv_nsec / 1000);
+  loop->real_time = ts.tv_sec S + ts.tv_nsec NS;
 }
 
 
@@ -2281,7 +2281,7 @@ io_update_time(void)
   if (rv < 0)
     die("clock_gettime: %m");
 
-  last_time = ((s64) ts.tv_sec S) + (ts.tv_nsec / 1000);
+  last_time = ts.tv_sec S + ts.tv_nsec NS;
 
   if (event_open)
   {