diff --git a/EcAlarmSinkSNMP.m b/EcAlarmSinkSNMP.m
index 077fd18..63b3f01 100644
--- a/EcAlarmSinkSNMP.m
+++ b/EcAlarmSinkSNMP.m
@@ -56,6 +56,12 @@ static NSLock		*classLock = nil;
 
 @end
 
+/* The ObjC __block define might conflict with system headers ...
+ *  */
+#if defined(__block)
+#undef __block
+#endif
+
 #include <net-snmp/net-snmp-config.h>
 #include <net-snmp/net-snmp-includes.h>
 #include <net-snmp/agent/net-snmp-agent-includes.h>