diff --git a/tests/streams/bstream.h b/tests/streams/bstream.h
index b1fe8aa326..51a27966c6 100644
--- a/tests/streams/bstream.h
+++ b/tests/streams/bstream.h
@@ -81,11 +81,18 @@ protected:
         CPPUNIT_ASSERT(!stream_in.Eof());
 
         // Size should be greater than zero.
-        // Note: streams not supporting this should register this test
-        //       with CPPUNIT_TEST_FAIL instead of CPPUNIT_TEST.
         CPPUNIT_ASSERT(stream_in.GetSize() != 0);
     }
 
+    // The variant for non-seekable streams.
+    void Input_GetSizeFail()
+    {
+        CleanupHelper cleanup(this);
+        const TStreamIn &stream_in = CreateInStream();
+
+        CPPUNIT_ASSERT(stream_in.GetSize() == 0);
+    }
+
     // Just try to perform a GetC() on the input stream.
     void Input_GetC()
     {
@@ -199,8 +206,6 @@ protected:
         CPPUNIT_ASSERT(!stream_in.Eof());
 
         // Try to Seek in the stream...
-        // Note: streams not supporting this should register this test
-        //       with CPPUNIT_TEST_FAIL instead of CPPUNIT_TEST.
         CPPUNIT_ASSERT_EQUAL(2, stream_in.SeekI(2, wxFromStart));
         CPPUNIT_ASSERT_EQUAL(4, stream_in.SeekI(2, wxFromCurrent));
         // Not sure the following line is correct, so test it differently.
@@ -210,6 +215,14 @@ protected:
         CPPUNIT_ASSERT((stream_in.SeekI(10, wxFromCurrent) == wxInvalidOffset) == m_bSeekInvalidBeyondEnd);
     }
 
+    void Input_SeekIFail()
+    {
+        CleanupHelper cleanup(this);
+        TStreamIn &stream_in = CreateInStream();
+
+        CPPUNIT_ASSERT( !stream_in.IsSeekable() );
+    }
+
     // Just try to perform a TellI() on the input stream.
     void Input_TellI()
     {
@@ -340,8 +353,6 @@ protected:
         (void)stream_out.Write(buf, 10);
 
         // Try to Seek in the stream...
-        // Note: streams not supporting this should register this test
-        //       with CPPUNIT_TEST_FAIL instead of CPPUNIT_TEST.
         CPPUNIT_ASSERT_EQUAL(2, stream_out.SeekO(2, wxFromStart));
         CPPUNIT_ASSERT_EQUAL(4, stream_out.SeekO(2, wxFromCurrent));
         // Not sure the following line is correct, so test it differently.
@@ -351,6 +362,14 @@ protected:
         CPPUNIT_ASSERT((stream_out.SeekO(10, wxFromCurrent) == wxInvalidOffset) == m_bSeekInvalidBeyondEnd);
     }
 
+    void Output_SeekOFail()
+    {
+        CleanupHelper cleanup(this);
+        TStreamOut &stream_out = CreateOutStream();
+
+        CPPUNIT_ASSERT( !stream_out.IsSeekable() );
+    }
+
     // Just try to perform a TellO() on the output stream.
     void Output_TellO()
     {
diff --git a/tests/streams/zlibstream.cpp b/tests/streams/zlibstream.cpp
index d11f1809d3..bc0275afa2 100644
--- a/tests/streams/zlibstream.cpp
+++ b/tests/streams/zlibstream.cpp
@@ -46,13 +46,13 @@ public:
 
     CPPUNIT_TEST_SUITE(zlibStream);
         // Base class stream tests the zlibstream supports.
-        CPPUNIT_TEST_FAIL(Input_GetSize);
+        CPPUNIT_TEST(Input_GetSizeFail);
         CPPUNIT_TEST(Input_GetC);
         CPPUNIT_TEST(Input_Read);
         CPPUNIT_TEST(Input_Eof);
         CPPUNIT_TEST(Input_LastRead);
         CPPUNIT_TEST(Input_CanRead);
-        CPPUNIT_TEST_FAIL(Input_SeekI);
+        CPPUNIT_TEST(Input_SeekIFail);
         CPPUNIT_TEST(Input_TellI);
         CPPUNIT_TEST(Input_Peek);
         CPPUNIT_TEST(Input_Ungetch);
@@ -60,7 +60,7 @@ public:
         CPPUNIT_TEST(Output_PutC);
         CPPUNIT_TEST(Output_Write);
         CPPUNIT_TEST(Output_LastWrite);
-        CPPUNIT_TEST_FAIL(Output_SeekO);
+        CPPUNIT_TEST(Output_SeekOFail);
         CPPUNIT_TEST(Output_TellO);
 
         // Other test specific for zlib stream test case.