diff --git a/utbot-framework/src/main/kotlin/org/utbot/framework/concrete/InstrumentationContext.kt b/utbot-framework/src/main/kotlin/org/utbot/framework/concrete/InstrumentationContext.kt
index 0233c7b6d9..09fba7410d 100644
--- a/utbot-framework/src/main/kotlin/org/utbot/framework/concrete/InstrumentationContext.kt
+++ b/utbot-framework/src/main/kotlin/org/utbot/framework/concrete/InstrumentationContext.kt
@@ -1,8 +1,8 @@
 package org.utbot.framework.concrete
 
-import org.utbot.framework.plugin.api.util.signature
 import java.lang.reflect.Method
 import java.util.IdentityHashMap
+import org.utbot.instrumentation.instrumentation.mock.computeKeyForMethod
 
 /**
  * Some information, which is computed after classes instrumentation.
@@ -66,7 +66,7 @@ class InstrumentationContext {
         }
 
         fun updateMocks(obj: Any?, method: Method, values: List<*>) {
-            updateMocks(obj, method.signature, values)
+            updateMocks(obj, computeKeyForMethod(method), values)
         }
     }
 }
diff --git a/utbot-framework/src/main/kotlin/org/utbot/framework/concrete/MethodMockController.kt b/utbot-framework/src/main/kotlin/org/utbot/framework/concrete/MethodMockController.kt
index 342c867a15..9b3ff5790f 100644
--- a/utbot-framework/src/main/kotlin/org/utbot/framework/concrete/MethodMockController.kt
+++ b/utbot-framework/src/main/kotlin/org/utbot/framework/concrete/MethodMockController.kt
@@ -1,11 +1,11 @@
 package org.utbot.framework.concrete
 
-import org.utbot.common.withAccessibility
-import org.utbot.framework.plugin.api.util.signature
-import org.utbot.instrumentation.instrumentation.mock.MockConfig
 import java.lang.reflect.Field
 import java.lang.reflect.Method
 import java.lang.reflect.Modifier
+import org.utbot.common.withAccessibility
+import org.utbot.instrumentation.instrumentation.mock.MockConfig
+import org.utbot.instrumentation.instrumentation.mock.computeKeyForMethod
 
 
 /**
@@ -31,7 +31,8 @@ class MethodMockController(
             error("$method is an instance method, but instance is null!")
         }
 
-        val id = instrumentationContext.methodSignatureToId[method.signature]
+        val computedSignature = computeKeyForMethod(method)
+        val id = instrumentationContext.methodSignatureToId[computedSignature]
 
         isMockField = clazz.declaredFields.firstOrNull { it.name == MockConfig.IS_MOCK_FIELD + id }
             ?: error("No field ${MockConfig.IS_MOCK_FIELD + id} in $clazz")
diff --git a/utbot-instrumentation/src/main/kotlin/org/utbot/instrumentation/instrumentation/mock/MockClassVisitor.kt b/utbot-instrumentation/src/main/kotlin/org/utbot/instrumentation/instrumentation/mock/MockClassVisitor.kt
index 37dceb7efe..ec108974e3 100644
--- a/utbot-instrumentation/src/main/kotlin/org/utbot/instrumentation/instrumentation/mock/MockClassVisitor.kt
+++ b/utbot-instrumentation/src/main/kotlin/org/utbot/instrumentation/instrumentation/mock/MockClassVisitor.kt
@@ -10,11 +10,21 @@ import org.objectweb.asm.Opcodes
 import org.objectweb.asm.Type
 import org.objectweb.asm.commons.AdviceAdapter
 import org.objectweb.asm.commons.Method.getMethod
+import org.utbot.framework.plugin.api.util.signature
 
 object MockConfig {
     const val IS_MOCK_FIELD = "\$__is_mock_"
 }
 
+/**
+ * Computes key for method that is used for mocking.
+ */
+fun computeKeyForMethod(internalType: String, methodSignature: String) =
+    "$internalType@$methodSignature"
+
+fun computeKeyForMethod(method: Method) =
+    computeKeyForMethod(Type.getInternalName(method.declaringClass), method.signature)
+
 class MockClassVisitor(
     classVisitor: ClassVisitor,
     mockGetter: Method,
@@ -73,7 +83,7 @@ class MockClassVisitor(
         val isStatic = access and Opcodes.ACC_STATIC != 0
         val isVoidMethod = Type.getReturnType(descriptor) == Type.VOID_TYPE
 
-        val computedSignature = name + descriptor
+        val computedSignature = computeKeyForMethod(internalClassName, "$name$descriptor")
         val id = signatureToId.size
         signatureToId[computedSignature] = id
 
diff --git a/utbot-instrumentation/src/test/kotlin/org/utbot/instrumentation/examples/mock/MockHelper.kt b/utbot-instrumentation/src/test/kotlin/org/utbot/instrumentation/examples/mock/MockHelper.kt
index e7b10fc982..b97879559b 100644
--- a/utbot-instrumentation/src/test/kotlin/org/utbot/instrumentation/examples/mock/MockHelper.kt
+++ b/utbot-instrumentation/src/test/kotlin/org/utbot/instrumentation/examples/mock/MockHelper.kt
@@ -1,14 +1,14 @@
 package org.utbot.instrumentation.examples.mock
 
-import org.utbot.common.withAccessibility
-import org.utbot.framework.plugin.api.util.signature
-import org.utbot.instrumentation.instrumentation.instrumenter.Instrumenter
-import org.utbot.instrumentation.instrumentation.mock.MockClassVisitor
-import org.utbot.instrumentation.instrumentation.mock.MockConfig
 import java.lang.reflect.Method
 import java.util.IdentityHashMap
 import kotlin.reflect.jvm.javaMethod
 import org.objectweb.asm.Type
+import org.utbot.common.withAccessibility
+import org.utbot.instrumentation.instrumentation.instrumenter.Instrumenter
+import org.utbot.instrumentation.instrumentation.mock.MockClassVisitor
+import org.utbot.instrumentation.instrumentation.mock.MockConfig
+import org.utbot.instrumentation.instrumentation.mock.computeKeyForMethod
 
 /**
  * Helper for generating tests with methods mocks.
@@ -52,8 +52,8 @@ class MockHelper(
             error("Can't mock function returning void!")
         }
 
-        val sign = method.signature
-        val methodId = mockClassVisitor.signatureToId[sign]
+        val computedSignature = computeKeyForMethod(method)
+        val methodId = mockClassVisitor.signatureToId[computedSignature]
 
         val isMockField = instrumentedClazz.getDeclaredField(MockConfig.IS_MOCK_FIELD + methodId)
         MockGetter.updateMocks(instance, method, mockedValues)
@@ -129,7 +129,7 @@ class MockHelper(
         }
 
         fun updateMocks(obj: Any?, method: Method, values: List<*>) {
-            updateMocks(obj, method.signature, values)
+            updateMocks(obj, computeKeyForMethod(method), values)
         }
     }
 }
\ No newline at end of file