diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/SignatureBuilder.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/SignatureBuilder.java
index c38912b1ce0..ea6c8115856 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/SignatureBuilder.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/SignatureBuilder.java
@@ -76,6 +76,14 @@ class SignatureBuilder implements ITypeMarshalBuffer {
 			putShort(NULL_TYPE);
 		} else if (type instanceof IBinding) {
 			marshalBinding((IBinding) type);
+		} else if (type instanceof UniqueType) {
+			// UniqueType is not an ISerializableType because there should never be
+			// a need to write it to the index, but it can appear in a signature
+			// during partial ordering of function templates.
+			appendSeparator();
+			fBuffer.append("Unique(@");  //$NON-NLS-1$
+			fBuffer.append(Integer.toHexString(System.identityHashCode(type)));
+			fBuffer.append(')');
 		} else {
 			assert false : "Cannot serialize " + ASTTypeUtil.getType(type) + " (" + type.getClass().getName() + ")"; //$NON-NLS-1$//$NON-NLS-2$//$NON-NLS-3$
 			putShort(UNSTORABLE_TYPE);
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/dom/TypeMarshalBuffer.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/dom/TypeMarshalBuffer.java
index 42288599aaa..f449ac771cd 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/dom/TypeMarshalBuffer.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/dom/TypeMarshalBuffer.java
@@ -136,7 +136,7 @@ public final class TypeMarshalBuffer implements ITypeMarshalBuffer {
 		} else if (type instanceof IBinding) {
 			marshalBinding((IBinding) type);
 		} else {
-			assert false : "Cannot serialize " + ASTTypeUtil.getType(type) + " (" + type.getClass().getName() + ")";   //$NON-NLS-1$//$NON-NLS-2$//$NON-NLS-3$
+			CCorePlugin.log("Cannot serialize " + ASTTypeUtil.getType(type) + " (" + type.getClass().getName() + ")");   //$NON-NLS-1$//$NON-NLS-2$//$NON-NLS-3$
 			putShort(UNSTORABLE_TYPE);
 		}
 	}