diff --git a/rust/ql/lib/codeql/rust/internal/typeinference/TypeInference.qll b/rust/ql/lib/codeql/rust/internal/typeinference/TypeInference.qll
index ebf7bd2aa82..e2b687a0079 100644
--- a/rust/ql/lib/codeql/rust/internal/typeinference/TypeInference.qll
+++ b/rust/ql/lib/codeql/rust/internal/typeinference/TypeInference.qll
@@ -134,12 +134,8 @@ class TypePath = M1::TypePath;
 
 module TypePath = M1::TypePath;
 
-private module Input2 implements InputSig2 {
-  private import TypeMention as TM
-
-  class TypeMention = TM::TypeMention;
-
-  TypeMention getABaseTypeMention(Type t) { none() }
+private module Input2 implements InputSig2<TypeMentionTypeTree> {
+  TypeMentionTypeTree getABaseTypeMention(Type t) { none() }
 
   Type getATypeParameterConstraint(TypeParameter tp, TypePath path) {
     exists(TypeMention tm | result = tm.resolveTypeAt(path) |
@@ -162,7 +158,8 @@ private module Input2 implements InputSig2 {
    * inference module for more information.
    */
   predicate conditionSatisfiesConstraint(
-    TypeAbstraction abs, TypeMention condition, TypeMention constraint, boolean transitive
+    TypeAbstraction abs, TypeMentionTypeTree condition, TypeMentionTypeTree constraint,
+    boolean transitive
   ) {
     // `impl` blocks implementing traits
     transitive = false and
@@ -212,7 +209,7 @@ private module Input2 implements InputSig2 {
   }
 }
 
-private module M2 = Make2<Input2>;
+private module M2 = Make2<TypeMentionTypeTree, Input2>;
 
 import M2
 
diff --git a/rust/ql/lib/codeql/rust/internal/typeinference/TypeMention.qll b/rust/ql/lib/codeql/rust/internal/typeinference/TypeMention.qll
index 063e9beffd3..7e5abaa5a3a 100644
--- a/rust/ql/lib/codeql/rust/internal/typeinference/TypeMention.qll
+++ b/rust/ql/lib/codeql/rust/internal/typeinference/TypeMention.qll
@@ -18,6 +18,13 @@ abstract class TypeMention extends AstNode {
   final Type resolveType() { result = this.resolveTypeAt(TypePath::nil()) }
 }
 
+final private class FinalTypeMention = TypeMention;
+
+/** An adapter for type mentions to implement `HasTypeTreeSig`. */
+final class TypeMentionTypeTree extends FinalTypeMention {
+  Type getTypeAt(TypePath path) { result = this.resolveTypeAt(path) }
+}
+
 class TupleTypeReprMention extends TypeMention instanceof TupleTypeRepr {
   override Type resolveTypeAt(TypePath path) {
     path.isEmpty() and