diff --git a/ospfd/ChangeLog b/ospfd/ChangeLog
index 825b92c..b33ca43 100644
--- a/ospfd/ChangeLog
+++ b/ospfd/ChangeLog
@@ -1,3 +1,8 @@
+2005-11-16 Andrew J. Schorr <ajschorr@alumni.princeton.edu>
+
+	* ospf_ism.h: (OSPF_ISM_TIMER_OFF) Improve macro syntax by enclosing
+	  in 'do {...} while(0)'.
+
 2005-11-14 Paul Jakma <paul.jakma@sun.com>
 
 	* ospfd.c: (ospf_new) stub-shutdown should just default to
diff --git a/ospfd/ospf_ism.h b/ospfd/ospf_ism.h
index c714a15..f0357a4 100644
--- a/ospfd/ospf_ism.h
+++ b/ospfd/ospf_ism.h
@@ -90,11 +90,13 @@
 
 /* Macro for OSPF ISM timer turn off. */
 #define OSPF_ISM_TIMER_OFF(X) \
-      if (X) \
-        { \
-          thread_cancel (X); \
-          (X) = NULL; \
-        }
+  do { \
+    if (X) \
+      { \
+	thread_cancel (X); \
+	(X) = NULL; \
+      } \
+  } while (0)
 
 /* Macro for OSPF schedule event. */
 #define OSPF_ISM_EVENT_SCHEDULE(I,E) \