diff --git a/compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/AlternativeSignatureData.java b/compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/AlternativeSignatureData.java
index 4c7d42e0681..e84ce3b18c9 100644
--- a/compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/AlternativeSignatureData.java
+++ b/compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/AlternativeSignatureData.java
@@ -296,14 +296,18 @@ class AlternativeSignatureData {
                 else {
                     JetTypeConstraint constraint =
                             findTypeParameterConstraint(altFunDeclaration, pd.getName(), upperBoundIndex);
-                    assert constraint != null; // TODO fail more properly
-                    JetTypeReference boundTypeReference = constraint.getBoundTypeReference();
-                    assert  boundTypeReference != null;
-                    altTypeElement = boundTypeReference.getTypeElement();
+                    if (constraint == null) {
+                        fail("Upper bound #%d for type parameter %s is missing", upperBoundIndex, pd.getName());
+                    }
+                    //noinspection ConstantConditions
+                    altTypeElement = constraint.getBoundTypeReference().getTypeElement();
                 }
                 altParamDescriptor.addUpperBound(computeType(altTypeElement, upperBound));
                 upperBoundIndex++;
             }
+            if (findTypeParameterConstraint(altFunDeclaration, pd.getName(), upperBoundIndex) != null) {
+                fail("Extra upper bound #%d for type parameter %s", upperBoundIndex, pd.getName());
+            }
 
             altParamDescriptor.setInitialized();
             altTypeParameters.add(altParamDescriptor);
diff --git a/compiler/testData/readJavaBinaryClass/kotlinSignature/error/ExtraUpperBound.java b/compiler/testData/readJavaBinaryClass/kotlinSignature/error/ExtraUpperBound.java
new file mode 100644
index 00000000000..d9155efb6a0
--- /dev/null
+++ b/compiler/testData/readJavaBinaryClass/kotlinSignature/error/ExtraUpperBound.java
@@ -0,0 +1,10 @@
+package test;
+
+import jet.runtime.typeinfo.KotlinSignature;
+
+public class ExtraUpperBound {
+    @KotlinSignature("fun <A : Runnable> foo() : String where A : Cloneable")
+    public <A extends Runnable> String foo() {
+        throw new UnsupportedOperationException();
+    }
+}
diff --git a/compiler/testData/readJavaBinaryClass/kotlinSignature/error/ExtraUpperBound.kt b/compiler/testData/readJavaBinaryClass/kotlinSignature/error/ExtraUpperBound.kt
new file mode 100644
index 00000000000..f254cca20bd
--- /dev/null
+++ b/compiler/testData/readJavaBinaryClass/kotlinSignature/error/ExtraUpperBound.kt
@@ -0,0 +1,9 @@
+package test
+
+import java.util.*
+
+public open class ExtraUpperBound : Object() {
+    public open fun <A : Runnable?> foo() : String? {
+        throw UnsupportedOperationException()
+    }
+}
diff --git a/compiler/testData/readJavaBinaryClass/kotlinSignature/error/ExtraUpperBound.txt b/compiler/testData/readJavaBinaryClass/kotlinSignature/error/ExtraUpperBound.txt
new file mode 100644
index 00000000000..9ab08656259
--- /dev/null
+++ b/compiler/testData/readJavaBinaryClass/kotlinSignature/error/ExtraUpperBound.txt
@@ -0,0 +1,6 @@
+namespace test
+
+public open class test.ExtraUpperBound : java.lang.Object {
+    public final /*constructor*/ fun <init>(): test.ExtraUpperBound
+    public open fun </*0*/ A : java.lang.Runnable?>foo(): jet.String?
+}
diff --git a/compiler/testData/readJavaBinaryClass/kotlinSignature/error/MissingUpperBound.java b/compiler/testData/readJavaBinaryClass/kotlinSignature/error/MissingUpperBound.java
new file mode 100644
index 00000000000..a32c5b2a4f4
--- /dev/null
+++ b/compiler/testData/readJavaBinaryClass/kotlinSignature/error/MissingUpperBound.java
@@ -0,0 +1,10 @@
+package test;
+
+import jet.runtime.typeinfo.KotlinSignature;
+
+public class MissingUpperBound {
+    @KotlinSignature("fun <A : Runnable> foo() : String")
+    public <A extends Runnable & Cloneable> String foo() {
+        throw new UnsupportedOperationException();
+    }
+}
diff --git a/compiler/testData/readJavaBinaryClass/kotlinSignature/error/MissingUpperBound.kt b/compiler/testData/readJavaBinaryClass/kotlinSignature/error/MissingUpperBound.kt
new file mode 100644
index 00000000000..60b9a7b62ab
--- /dev/null
+++ b/compiler/testData/readJavaBinaryClass/kotlinSignature/error/MissingUpperBound.kt
@@ -0,0 +1,9 @@
+package test
+
+import java.util.*
+
+public open class MissingUpperBound : Object() {
+    public open fun <A : Runnable?> foo() : String? where A : Cloneable? {
+        throw UnsupportedOperationException()
+    }
+}
diff --git a/compiler/testData/readJavaBinaryClass/kotlinSignature/error/MissingUpperBound.txt b/compiler/testData/readJavaBinaryClass/kotlinSignature/error/MissingUpperBound.txt
new file mode 100644
index 00000000000..9fab2b1afde
--- /dev/null
+++ b/compiler/testData/readJavaBinaryClass/kotlinSignature/error/MissingUpperBound.txt
@@ -0,0 +1,6 @@
+namespace test
+
+public open class test.MissingUpperBound : java.lang.Object {
+    public final /*constructor*/ fun <init>(): test.MissingUpperBound
+    public open fun </*0*/ A : java.lang.Cloneable? & java.lang.Runnable?>foo(): jet.String?
+}