--- EV/EV.xs	2007/10/31 11:52:11	1.17
+++ EV/EV.xs	2007/10/31 11:55:42	1.18
@@ -213,6 +213,9 @@
 }
 #endif
 
+#define CHECK_REPEAT(repeat) if (repeat < 0.) \
+  croak (# repeat " value must be >= 0");
+
 /////////////////////////////////////////////////////////////////////////////
 // XS interface functions
 
@@ -326,6 +329,8 @@
 struct ev_timer *timer (NV after, NV repeat, SV *cb)
 	ALIAS:
         timer_ns = 1
+        INIT:
+        CHECK_REPEAT (repeat);
 	CODE:
         RETVAL = e_new (sizeof (struct ev_timer), cb);
         evtimer_set (RETVAL, after, repeat);
@@ -336,6 +341,8 @@
 struct ev_periodic *periodic (NV at, NV interval, SV *cb)
 	ALIAS:
         periodic_ns = 1
+        INIT:
+        CHECK_REPEAT (interval);
 	CODE:
         RETVAL = e_new (sizeof (struct ev_periodic), cb);
         evperiodic_set (RETVAL, at, interval);
@@ -468,12 +475,18 @@
 MODULE = EV		PACKAGE = EV::Timer	PREFIX = evtimer_
 
 void evtimer_start (struct ev_timer *w)
+        INIT:
+        CHECK_REPEAT (w->repeat);
 
 void evtimer_stop (struct ev_timer *w)
 
 void evtimer_again (struct ev_timer *w)
+        INIT:
+        CHECK_REPEAT (w->repeat);
 
 void set (struct ev_timer *w, NV after, NV repeat = 0.)
+        INIT:
+        CHECK_REPEAT (repeat);
 	CODE:
 {
         int active = w->active;
@@ -485,10 +498,14 @@
 MODULE = EV		PACKAGE = EV::Periodic	PREFIX = evperiodic_
 
 void evperiodic_start (struct ev_periodic *w)
+        INIT:
+        CHECK_REPEAT (w->interval);
 
 void evperiodic_stop (struct ev_periodic *w)
 
 void set (struct ev_periodic *w, NV at, NV interval = 0.)
+        INIT:
+        CHECK_REPEAT (interval);
 	CODE:
 {
         int active = w->active;