diff --git a/python/testData/debug/test_step_into_with_threads.py b/python/testData/debug/test_step_into_with_threads.py
new file mode 100644
index 000000000000..ed3f9b5c40f8
--- /dev/null
+++ b/python/testData/debug/test_step_into_with_threads.py
@@ -0,0 +1,23 @@
+from __future__ import print_function
+import threading
+
+
+class A(threading.Thread):
+    def foo(self):
+        print("foo")
+
+    def bar(self):
+        print("bar")
+
+    def baz(self):
+        print("baz")
+
+    def run(self):
+        self.foo()  # breakpoint
+        self.bar()
+        self.baz()  # breakpoint
+
+
+if __name__ == '__main__':
+    t = A()
+    t.start()
\ No newline at end of file
diff --git a/python/testSrc/com/jetbrains/env/PyExecutionFixtureTestTask.java b/python/testSrc/com/jetbrains/env/PyExecutionFixtureTestTask.java
index 70e11c6317b5..2e474bea578f 100644
--- a/python/testSrc/com/jetbrains/env/PyExecutionFixtureTestTask.java
+++ b/python/testSrc/com/jetbrains/env/PyExecutionFixtureTestTask.java
@@ -173,7 +173,7 @@ public abstract class PyExecutionFixtureTestTask extends PyTestTask {
 
   protected String getFilePath(@NotNull final String path) {
     final VirtualFile virtualFile = myFixture.getTempDirFixture().getFile(path);
-    assert virtualFile != null && virtualFile.exists() : String.format("No file in %s", myFixture.getTempDirPath());
+    assert virtualFile != null && virtualFile.exists() : String.format("No file '%s' in %s", path,  myFixture.getTempDirPath());
     return virtualFile.getPath();
   }
 
diff --git a/python/testSrc/com/jetbrains/env/python/PythonDebuggerTest.java b/python/testSrc/com/jetbrains/env/python/PythonDebuggerTest.java
index 9c6cde8286f9..0b1ca294728e 100644
--- a/python/testSrc/com/jetbrains/env/python/PythonDebuggerTest.java
+++ b/python/testSrc/com/jetbrains/env/python/PythonDebuggerTest.java
@@ -2283,7 +2283,7 @@ public class PythonDebuggerTest extends PyEnvTestCase {
 
       @Override
       public void before() throws Exception {
-        toggleBreakpoint(getScriptName(), 8);
+        toggleBreakpoint(getFilePath(getScriptName()), 8);
       }
 
       @Override
@@ -2328,4 +2328,35 @@ public class PythonDebuggerTest extends PyEnvTestCase {
       }
     });
   }
+
+  @Test
+  public void testStepIntoWithThreads() {
+    runPythonTest(new PyDebuggerTask("/debug", "test_step_into_with_threads.py") {
+      @Override
+      public void before() {
+        toggleBreakpoint(getFilePath(getScriptName()), 15);
+        toggleBreakpoint(getFilePath(getScriptName()), 17);
+      }
+
+      @Override
+      public void testing() throws Exception {
+        waitForPause();
+        stepInto();
+        waitForPause();
+        stepOver();
+        waitForPause();
+        waitForOutput("foo");
+        resume();
+        waitForOutput("bar");
+        waitForPause();
+        stepInto();
+        waitForPause();
+        stepOver();
+        waitForPause();
+        waitForOutput("baz");
+        resume();
+        waitForTerminate();
+      }
+    });
+  }
 }
diff --git a/python/testSrc/com/jetbrains/env/python/debug/PyBaseDebuggerTask.java b/python/testSrc/com/jetbrains/env/python/debug/PyBaseDebuggerTask.java
index 83058a1a35ca..24587864c549 100644
--- a/python/testSrc/com/jetbrains/env/python/debug/PyBaseDebuggerTask.java
+++ b/python/testSrc/com/jetbrains/env/python/debug/PyBaseDebuggerTask.java
@@ -101,7 +101,7 @@ public abstract class PyBaseDebuggerTask extends PyExecutionFixtureTestTask {
   protected void resume() {
     XDebugSession currentSession = XDebuggerManager.getInstance(getProject()).getCurrentSession();
 
-    Assert.assertTrue(currentSession.isSuspended());
+    Assert.assertTrue("Resume called for session that is not in suspended state", currentSession.isSuspended());
     Assert.assertEquals(0, myPausedSemaphore.availablePermits());
 
     currentSession.resume();
@@ -110,7 +110,7 @@ public abstract class PyBaseDebuggerTask extends PyExecutionFixtureTestTask {
   protected void stepOver() {
     XDebugSession currentSession = XDebuggerManager.getInstance(getProject()).getCurrentSession();
 
-    Assert.assertTrue(currentSession.isSuspended());
+    Assert.assertTrue("Step over called for session that is not in suspended state", currentSession.isSuspended());
     Assert.assertEquals(0, myPausedSemaphore.availablePermits());
 
     currentSession.stepOver(false);
@@ -119,7 +119,7 @@ public abstract class PyBaseDebuggerTask extends PyExecutionFixtureTestTask {
   protected void stepInto() {
     XDebugSession currentSession = XDebuggerManager.getInstance(getProject()).getCurrentSession();
 
-    Assert.assertTrue(currentSession.isSuspended());
+    Assert.assertTrue("Step into called for session that is not in suspended state", currentSession.isSuspended());
     Assert.assertEquals(0, myPausedSemaphore.availablePermits());
 
     currentSession.stepInto();