diff --git a/bundles/org.eclipse.ui.ide/src/org/eclipse/ui/internal/ide/DirectoryProposalContentAssist.java b/bundles/org.eclipse.ui.ide/src/org/eclipse/ui/internal/ide/DirectoryProposalContentAssist.java
index 8c450506f7c..a6b82e9fd8d 100644
--- a/bundles/org.eclipse.ui.ide/src/org/eclipse/ui/internal/ide/DirectoryProposalContentAssist.java
+++ b/bundles/org.eclipse.ui.ide/src/org/eclipse/ui/internal/ide/DirectoryProposalContentAssist.java
@@ -165,7 +165,7 @@ public DirectoryProposalAutoCompleteField(Control control, IControlContentAdapte
 			proposalProvider = new FileNameSubstringMatchContentProposalProvider();
 			KeyStroke triggeringKeyStroke = safeKeyStroke("Ctrl+Space"); //$NON-NLS-1$
 			adapter = new OpenableContentProposalAdapter(control, controlContentAdapter, proposalProvider,
-					triggeringKeyStroke, null);
+					triggeringKeyStroke, new char[] { '/', '\\' });
 			adapter.setPropagateKeys(true);
 			adapter.setProposalAcceptanceStyle(ContentProposalAdapter.PROPOSAL_REPLACE);
 		}