diff --git a/platform/lang-api/src/com/intellij/execution/filters/CompositeInputFilter.java b/platform/lang-api/src/com/intellij/execution/filters/CompositeInputFilter.java
index af685bf8dbe0..7929a2b350bc 100644
--- a/platform/lang-api/src/com/intellij/execution/filters/CompositeInputFilter.java
+++ b/platform/lang-api/src/com/intellij/execution/filters/CompositeInputFilter.java
@@ -41,7 +41,7 @@ public class CompositeInputFilter implements InputFilter {
 
   @Override
   @Nullable
-  public List<Pair<String, ConsoleViewContentType>> applyFilter(@NotNull final String text, final ConsoleViewContentType contentType) {
+  public List<Pair<String, ConsoleViewContentType>> applyFilter(@NotNull final String text, @NotNull final ConsoleViewContentType contentType) {
     boolean dumb = myDumbService.isDumb();
     for (Pair<InputFilter, Boolean> pair : myFilters) {
       if (!dumb || pair.second == Boolean.TRUE) {
@@ -66,7 +66,7 @@ public class CompositeInputFilter implements InputFilter {
 
       @Nullable
       @Override
-      public List<Pair<String, ConsoleViewContentType>> applyFilter(@NotNull String text, ConsoleViewContentType contentType) {
+      public List<Pair<String, ConsoleViewContentType>> applyFilter(@NotNull String text, @NotNull ConsoleViewContentType contentType) {
         if (!isBroken) {
           try {
             return filter.applyFilter(text, contentType);
diff --git a/platform/lang-api/src/com/intellij/execution/filters/InputFilter.java b/platform/lang-api/src/com/intellij/execution/filters/InputFilter.java
index e4225b102fb0..c0d6dcfd4f53 100644
--- a/platform/lang-api/src/com/intellij/execution/filters/InputFilter.java
+++ b/platform/lang-api/src/com/intellij/execution/filters/InputFilter.java
@@ -30,6 +30,6 @@ public interface InputFilter {
    * @return            <tt>null</tt>, if there was no match, otherwise, a list of pairs like ('string to use', 'content type to use')
    */
   @Nullable
-  List<Pair<String, ConsoleViewContentType>> applyFilter(@NotNull  String text, ConsoleViewContentType contentType);
+  List<Pair<String, ConsoleViewContentType>> applyFilter(@NotNull  String text, @NotNull ConsoleViewContentType contentType);
 
 }
diff --git a/python/educational-python/src/com/jetbrains/python/edu/debugger/PyEduConsoleInputFilterProvider.java b/python/educational-python/src/com/jetbrains/python/edu/debugger/PyEduConsoleInputFilterProvider.java
index 1ebb3a7539fe..b3e19df57008 100644
--- a/python/educational-python/src/com/jetbrains/python/edu/debugger/PyEduConsoleInputFilterProvider.java
+++ b/python/educational-python/src/com/jetbrains/python/edu/debugger/PyEduConsoleInputFilterProvider.java
@@ -16,7 +16,7 @@ public class PyEduConsoleInputFilterProvider implements ConsoleInputFilterProvid
   public InputFilter[] getDefaultFilters(@NotNull Project project) {
     return new InputFilter[]{new InputFilter() {
       @Override
-      public List<Pair<String, ConsoleViewContentType>> applyFilter(@NotNull String text, ConsoleViewContentType outputType) {
+      public List<Pair<String, ConsoleViewContentType>> applyFilter(@NotNull String text, @NotNull ConsoleViewContentType outputType) {
         if (outputType.equals(ConsoleViewContentType.SYSTEM_OUTPUT) && !text.contains("exit code")) {
           return Collections.emptyList();
         }