diff --git a/core/org.eclipse.cdt.ui/plugin.xml b/core/org.eclipse.cdt.ui/plugin.xml
index 8ec24ee3628..28ee3dc819d 100644
--- a/core/org.eclipse.cdt.ui/plugin.xml
+++ b/core/org.eclipse.cdt.ui/plugin.xml
@@ -1488,6 +1488,7 @@
             class="org.eclipse.cdt.internal.ui.text.contentassist.LegacyCompletionProposalComputer"
             categoryId="org.eclipse.cdt.ui.parserProposalCategory">
             <partition type="__dftl_partition_content_type"/>
+            <partition type="__c_preprocessor"/>
         </completionProposalComputer>
     </extension>
     <!-- template proposals -->
@@ -1511,6 +1512,7 @@
             <partition type="__c_singleline_comment"/>
             <partition type="__c_multiline_comment"/>
             <partition type="__c_string"/>
+            <partition type="__c_preprocessor"/>
         </completionProposalComputer>
     </extension>