diff --git a/CHANGES b/CHANGES
index 2f4df7415d..185853896d 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,4 +1,9 @@
 
+2.3-599 | 2015-03-25 10:14:57 -0700
+
+  * Add defensive checks in code to calculate log rotation intervals.
+    (Pete Nelson).
+
 2.3-597 | 2015-03-23 12:50:04 -0700
 
   * DTLS analyzer. (Johanna Amann)
diff --git a/VERSION b/VERSION
index fce1937546..d12f607b2f 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-2.3-597
+2.3-599
diff --git a/src/util.cc b/src/util.cc
index ac2a942ed3..501f87e57d 100644
--- a/src/util.cc
+++ b/src/util.cc
@@ -1352,13 +1352,23 @@ double parse_rotate_base_time(const char* rotate_base_time)
 
 double calc_next_rotate(double current, double interval, double base)
 	{
+	if ( ! interval )
+		{
+		reporter->Error("calc_next_rotate(): interval is zero, falling back to 24hrs");
+		interval = 86400;
+		}
+
 	// Calculate start of day.
 	time_t teatime = time_t(current);
 
 	struct tm t;
-	t = *localtime_r(&teatime, &t);
-	t.tm_hour = t.tm_min = t.tm_sec = 0;
-	double startofday = mktime(&t);
+	if ( ! localtime_r(&teatime, &t) )
+		{
+		reporter->Error("calc_next_rotate(): failure processing current time (%.6f)", current);
+
+		// fall back to the method used if no base time is given
+		base = -1;
+		}
 
 	if ( base < 0 )
 		// No base time given. To get nice timestamps, we round
@@ -1366,6 +1376,9 @@ double calc_next_rotate(double current, double interval, double base)
 		return floor(current / interval) * interval
 			+ interval - current;
 
+	t.tm_hour = t.tm_min = t.tm_sec = 0;
+	double startofday = mktime(&t);
+
 	// current < startofday + base + i * interval <= current + interval
 	return startofday + base +
 		ceil((current - startofday - base) / interval) * interval -