diff --git a/library/network/protocol/content_negotiation/conneg-safe.ecf b/library/network/protocol/content_negotiation/conneg-safe.ecf
index 06a7bda6..db815799 100644
--- a/library/network/protocol/content_negotiation/conneg-safe.ecf
+++ b/library/network/protocol/content_negotiation/conneg-safe.ecf
@@ -9,7 +9,7 @@
 			<exclude>/.svn$</exclude>
 		</file_rule>
 		<option warning="true" full_class_checking="true" is_attached_by_default="true" void_safety="all" syntax="standard">
-			<assertions precondition="true"/>
+			<assertions precondition="true" postcondition="true" invariant="true"/>
 		</option>
 		<library name="base" location="$ISE_LIBRARY\library\base\base-safe.ecf"/>
 		<library name="http" location="..\http\http-safe.ecf" readonly="false"/>