diff --git a/src/modules/audio_coding/codecs/iSAC/fix/source/lpc_masking_model.h b/src/modules/audio_coding/codecs/iSAC/fix/source/lpc_masking_model.h
index 351b41601..189e0e030 100644
--- a/src/modules/audio_coding/codecs/iSAC/fix/source/lpc_masking_model.h
+++ b/src/modules/audio_coding/codecs/iSAC/fix/source/lpc_masking_model.h
@@ -18,6 +18,10 @@
 #ifndef WEBRTC_MODULES_AUDIO_CODING_CODECS_ISAC_FIX_SOURCE_LPC_MASKING_MODEL_H_
 #define WEBRTC_MODULES_AUDIO_CODING_CODECS_ISAC_FIX_SOURCE_LPC_MASKING_MODEL_H_
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 #include "structs.h"
 
 int32_t WebRtcIsacfix_CalculateResidualEnergy(int lpc_order,
@@ -41,4 +45,8 @@ void WebRtcIsacfix_GetLpcCoef(WebRtc_Word16 *inLoQ0,
                               WebRtc_Word16 *lo_coeffQ15,
                               WebRtc_Word16 *hi_coeffQ15);
 
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+
 #endif /* WEBRTC_MODULES_AUDIO_CODING_CODECS_ISAC_FIX_SOURCE_LPC_MASKING_MODEL_H_ */
diff --git a/src/modules/audio_coding/codecs/iSAC/fix/source/structs.h b/src/modules/audio_coding/codecs/iSAC/fix/source/structs.h
index 54dffa924..bd7adc44b 100644
--- a/src/modules/audio_coding/codecs/iSAC/fix/source/structs.h
+++ b/src/modules/audio_coding/codecs/iSAC/fix/source/structs.h
@@ -19,9 +19,9 @@
 #define WEBRTC_MODULES_AUDIO_CODING_CODECS_ISAC_FIX_SOURCE_STRUCTS_H_
 
 
+#include "common_audio/signal_processing/include/signal_processing_library.h"
+#include "modules/audio_coding/codecs/iSAC/fix/source/settings.h"
 #include "typedefs.h"
-#include "signal_processing_library.h"
-#include "settings.h"
 
 /* Bitstream struct for decoder */
 typedef struct Bitstreamstruct_dec {
diff --git a/src/modules/audio_coding/codecs/iSAC/fix/test/isacfix_unittest.cc b/src/modules/audio_coding/codecs/iSAC/fix/test/isacfix_unittest.cc
new file mode 100644
index 000000000..b6a4b0e05
--- /dev/null
+++ b/src/modules/audio_coding/codecs/iSAC/fix/test/isacfix_unittest.cc
@@ -0,0 +1,33 @@
+/*
+ *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+#include <typedefs.h>
+
+#include "gtest/gtest.h"
+#include "modules/audio_coding/codecs/iSAC/fix/source/lpc_masking_model.h"
+
+class IsacUnitTest : public testing::Test {
+};
+
+TEST_F(IsacUnitTest, CalculateResidualEnergyTest) {
+  const int kIntOrder = 10;
+  const int32_t kInt32QDomain = 5;
+  const int kIntShift = 11;
+  int16_t a[kIntOrder + 1] = {32760, 122, 7, 0, -32760, -3958,
+      -48, 18745, 498, 9, 23456};
+  int32_t corr[kIntOrder + 1] = {11443647, -27495, 0,
+      98745, -11443600, 1, 1, 498, 9, 888, 23456};
+  int q_shift_residual = 0;
+  int32_t residual_energy = 0;
+
+  residual_energy = WebRtcIsacfix_CalculateResidualEnergy(kIntOrder,
+      kInt32QDomain, kIntShift, a, corr, &q_shift_residual);
+  EXPECT_EQ(1789023310, residual_energy);
+  EXPECT_EQ(2, q_shift_residual);
+}
diff --git a/src/modules/audio_coding/codecs/iSAC/isacfix_test.gypi b/src/modules/audio_coding/codecs/iSAC/isacfix_test.gypi
index e40a67212..a6c59d05a 100644
--- a/src/modules/audio_coding/codecs/iSAC/isacfix_test.gypi
+++ b/src/modules/audio_coding/codecs/iSAC/isacfix_test.gypi
@@ -1,4 +1,4 @@
-# Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
+# Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
 #
 # Use of this source code is governed by a BSD-style license
 # that can be found in the LICENSE file in the root of the source
@@ -23,13 +23,19 @@
         './fix/test/kenny.c',
       ],
     },
+    {
+      'target_name': 'isacfix_unittests',
+      'type': 'executable',
+      'dependencies': [
+        'iSACFix',
+        '<(DEPTH)/testing/gtest.gyp:gtest',
+        '<(webrtc_root)/test/test.gyp:test_support_main',
+      ],
+      'sources': [
+        'fix/test/isacfix_unittest.cc',
+      ],
+    },
   ],
 }
 
-# Local Variables:
-# tab-width:2
-# indent-tabs-mode:nil
-# End:
-# vim: set expandtab tabstop=2 shiftwidth=2:
-
 # TODO(kma): Add bit-exact test for iSAC-fix.