diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/calls/inference/ConstraintsSystem.java b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/calls/inference/ConstraintsSystem.java
index d21563ed220..c3aeda4ea26 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/calls/inference/ConstraintsSystem.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/calls/inference/ConstraintsSystem.java
@@ -45,10 +45,10 @@ public interface ConstraintsSystem {
      * @param constrainingType
      * @param constraintPosition
      */
-    void addSubtypingConstraint(@NotNull JetType subjectType, @NotNull JetType constrainingType, @NotNull ConstraintPosition constraintPosition);
+    void addSubtypingConstraint(@NotNull JetType subjectType, @Nullable JetType constrainingType, @NotNull ConstraintPosition constraintPosition);
 
     // only subject type might contain type variables
-    void addSupertypeConstraint(@NotNull JetType subjectType, @NotNull JetType constrainingType, @NotNull ConstraintPosition constraintPosition);
+    void addSupertypeConstraint(@NotNull JetType subjectType, @Nullable JetType constrainingType, @NotNull ConstraintPosition constraintPosition);
 
     boolean isSuccessful();
 
@@ -62,6 +62,8 @@ public interface ConstraintsSystem {
 
     boolean hasTypeConstructorMismatchAt(@NotNull ConstraintPosition constraintPosition);
 
+    boolean hasErrorInConstrainingTypes();
+
     @Nullable
     TypeConstraints getTypeConstraints(@NotNull TypeParameterDescriptor typeParameterDescriptor);
 
diff --git a/compiler/testData/diagnostics/tests/inference/hasErrorInConstrainingTypes.kt b/compiler/testData/diagnostics/tests/inference/hasErrorInConstrainingTypes.kt
new file mode 100644
index 00000000000..facb21165a5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/hasErrorInConstrainingTypes.kt
@@ -0,0 +1,8 @@
+package n
+
+fun foo<T>(<!UNUSED_PARAMETER!>t<!>: T, <!UNUSED_PARAMETER!>t1<!>: T) {}
+
+fun test() {
+    //no type inference error
+    foo(<!UNRESOLVED_REFERENCE!>aaab<!>, <!UNRESOLVED_REFERENCE!>bbb<!>)
+}
\ No newline at end of file