diff --git a/compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/kotlinSignature/PropagationHeuristics.java b/compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/kotlinSignature/PropagationHeuristics.java
index 39320c0b158..4b873a89ad7 100644
--- a/compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/kotlinSignature/PropagationHeuristics.java
+++ b/compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/kotlinSignature/PropagationHeuristics.java
@@ -224,7 +224,7 @@ class PropagationHeuristics {
                 JavaType value = entry.getValue();
                 erasedMap.put(entry.getKey(), value == null ? null : erasure(value));
             }
-            return JavaTypeSubstitutor.create(erasedMap);
+            return JavaTypeSubstitutorImpl.create(erasedMap);
         }
 
         private static boolean canHaveSuperMethod(@NotNull JavaMethod method) {
diff --git a/compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/structure/JavaClassifierTypeImpl.java b/compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/structure/JavaClassifierTypeImpl.java
index 8da3a300346..5b148c57aba 100644
--- a/compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/structure/JavaClassifierTypeImpl.java
+++ b/compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/structure/JavaClassifierTypeImpl.java
@@ -72,7 +72,7 @@ public class JavaClassifierTypeImpl extends JavaTypeImpl implements JavaClassifi
             PsiClass psiClass = result.getElement();
             resolutionResult = new ResolutionResult(
                     psiClass == null ? null : JavaClassifierImpl.create(psiClass),
-                    new JavaTypeSubstitutor(result.getSubstitutor())
+                    new JavaTypeSubstitutorImpl(result.getSubstitutor())
             );
         }
     }
diff --git a/compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/structure/JavaTypeSubstitutor.java b/compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/structure/JavaTypeSubstitutor.java
index a10dfa91ef7..65301ca77e8 100644
--- a/compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/structure/JavaTypeSubstitutor.java
+++ b/compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/structure/JavaTypeSubstitutor.java
@@ -17,83 +17,20 @@
 package org.jetbrains.jet.lang.resolve.java.structure;
 
 import com.intellij.psi.PsiSubstitutor;
-import com.intellij.psi.PsiType;
-import com.intellij.psi.PsiTypeParameter;
-import com.intellij.psi.impl.PsiSubstitutorImpl;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
-import java.util.HashMap;
 import java.util.Map;
 
-public class JavaTypeSubstitutor {
-    public static final JavaTypeSubstitutor EMPTY = new JavaTypeSubstitutor(PsiSubstitutor.EMPTY);
-
-    private final PsiSubstitutor psiSubstitutor;
-    private Map<JavaTypeParameter, JavaType> substitutionMap;
-
-    public JavaTypeSubstitutor(@NotNull PsiSubstitutor psiSubstitutor) {
-        this.psiSubstitutor = psiSubstitutor;
-    }
-
-    public JavaTypeSubstitutor(@NotNull PsiSubstitutor psiSubstitutor, @NotNull Map<JavaTypeParameter, JavaType> substitutionMap) {
-        this(psiSubstitutor);
-        this.substitutionMap = substitutionMap;
-    }
+public interface JavaTypeSubstitutor {
+    JavaTypeSubstitutor EMPTY = new JavaTypeSubstitutorImpl(PsiSubstitutor.EMPTY);
 
     @NotNull
-    public PsiSubstitutor getPsi() {
-        return psiSubstitutor;
-    }
-
-    @NotNull
-    public static JavaTypeSubstitutor create(@NotNull Map<JavaTypeParameter, JavaType> substitutionMap) {
-        Map<PsiTypeParameter, PsiType> psiMap = new HashMap<PsiTypeParameter, PsiType>();
-        for (Map.Entry<JavaTypeParameter, JavaType> entry : substitutionMap.entrySet()) {
-            JavaType value = entry.getValue();
-            psiMap.put(entry.getKey().getPsi(), value == null ? null : value.getPsi());
-        }
-        PsiSubstitutor psiSubstitutor = PsiSubstitutorImpl.createSubstitutor(psiMap);
-        return new JavaTypeSubstitutor(psiSubstitutor, substitutionMap);
-    }
-
-    @NotNull
-    public JavaType substitute(@NotNull JavaType type) {
-        return JavaTypeImpl.create(getPsi().substitute(type.getPsi()));
-    }
+    JavaType substitute(@NotNull JavaType type);
 
     @Nullable
-    public JavaType substitute(@NotNull JavaTypeParameter typeParameter) {
-        PsiType psiType = getPsi().substitute(typeParameter.getPsi());
-        return psiType == null ? null : JavaTypeImpl.create(psiType);
-    }
+    JavaType substitute(@NotNull JavaTypeParameter typeParameter);
 
     @NotNull
-    public Map<JavaTypeParameter, JavaType> getSubstitutionMap() {
-        if (substitutionMap == null) {
-            Map<PsiTypeParameter, PsiType> psiMap = psiSubstitutor.getSubstitutionMap();
-            substitutionMap = new HashMap<JavaTypeParameter, JavaType>();
-            for (Map.Entry<PsiTypeParameter, PsiType> entry : psiMap.entrySet()) {
-                PsiType value = entry.getValue();
-                substitutionMap.put(new JavaTypeParameterImpl(entry.getKey()), value == null ? null : JavaTypeImpl.create(value));
-            }
-        }
-
-        return substitutionMap;
-    }
-
-    @Override
-    public int hashCode() {
-        return getPsi().hashCode();
-    }
-
-    @Override
-    public boolean equals(Object obj) {
-        return obj instanceof JavaTypeSubstitutor && getPsi().equals(((JavaTypeSubstitutor) obj).getPsi());
-    }
-
-    @Override
-    public String toString() {
-        return getClass().getSimpleName() + ": " + getPsi();
-    }
+    Map<JavaTypeParameter, JavaType> getSubstitutionMap();
 }
diff --git a/compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/structure/JavaTypeSubstitutorImpl.java b/compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/structure/JavaTypeSubstitutorImpl.java
new file mode 100644
index 00000000000..e4b19105a83
--- /dev/null
+++ b/compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/structure/JavaTypeSubstitutorImpl.java
@@ -0,0 +1,95 @@
+/*
+ * Copyright 2010-2013 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.jetbrains.jet.lang.resolve.java.structure;
+
+import com.intellij.psi.PsiSubstitutor;
+import com.intellij.psi.PsiType;
+import com.intellij.psi.PsiTypeParameter;
+import com.intellij.psi.impl.PsiSubstitutorImpl;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.HashMap;
+import java.util.Map;
+
+public class JavaTypeSubstitutorImpl implements JavaTypeSubstitutor {
+    private final PsiSubstitutor psiSubstitutor;
+    private Map<JavaTypeParameter, JavaType> substitutionMap;
+
+    public JavaTypeSubstitutorImpl(@NotNull PsiSubstitutor psiSubstitutor) {
+        this.psiSubstitutor = psiSubstitutor;
+    }
+
+    public JavaTypeSubstitutorImpl(@NotNull PsiSubstitutor psiSubstitutor, @NotNull Map<JavaTypeParameter, JavaType> substitutionMap) {
+        this(psiSubstitutor);
+        this.substitutionMap = substitutionMap;
+    }
+
+    @NotNull
+    public static JavaTypeSubstitutor create(@NotNull Map<JavaTypeParameter, JavaType> substitutionMap) {
+        Map<PsiTypeParameter, PsiType> psiMap = new HashMap<PsiTypeParameter, PsiType>();
+        for (Map.Entry<JavaTypeParameter, JavaType> entry : substitutionMap.entrySet()) {
+            JavaType value = entry.getValue();
+            psiMap.put(entry.getKey().getPsi(), value == null ? null : value.getPsi());
+        }
+        PsiSubstitutor psiSubstitutor = PsiSubstitutorImpl.createSubstitutor(psiMap);
+        return new JavaTypeSubstitutorImpl(psiSubstitutor, substitutionMap);
+    }
+
+    @Override
+    @NotNull
+    public JavaType substitute(@NotNull JavaType type) {
+        return JavaTypeImpl.create(psiSubstitutor.substitute(type.getPsi()));
+    }
+
+    @Override
+    @Nullable
+    public JavaType substitute(@NotNull JavaTypeParameter typeParameter) {
+        PsiType psiType = psiSubstitutor.substitute(typeParameter.getPsi());
+        return psiType == null ? null : JavaTypeImpl.create(psiType);
+    }
+
+    @Override
+    @NotNull
+    public Map<JavaTypeParameter, JavaType> getSubstitutionMap() {
+        if (substitutionMap == null) {
+            Map<PsiTypeParameter, PsiType> psiMap = psiSubstitutor.getSubstitutionMap();
+            substitutionMap = new HashMap<JavaTypeParameter, JavaType>();
+            for (Map.Entry<PsiTypeParameter, PsiType> entry : psiMap.entrySet()) {
+                PsiType value = entry.getValue();
+                substitutionMap.put(new JavaTypeParameterImpl(entry.getKey()), value == null ? null : JavaTypeImpl.create(value));
+            }
+        }
+
+        return substitutionMap;
+    }
+
+    @Override
+    public int hashCode() {
+        return psiSubstitutor.hashCode();
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        return obj instanceof JavaTypeSubstitutorImpl && psiSubstitutor.equals(((JavaTypeSubstitutorImpl) obj).psiSubstitutor);
+    }
+
+    @Override
+    public String toString() {
+        return getClass().getSimpleName() + ": " + psiSubstitutor;
+    }
+}