diff --git a/src/modules/audio_coding/codecs/isac/fix/source/lpc_masking_model.c b/src/modules/audio_coding/codecs/isac/fix/source/lpc_masking_model.c
index 4212a4d309..ae5c90a880 100644
--- a/src/modules/audio_coding/codecs/isac/fix/source/lpc_masking_model.c
+++ b/src/modules/audio_coding/codecs/isac/fix/source/lpc_masking_model.c
@@ -519,9 +519,9 @@ int32_t WebRtcIsacfix_CalculateResidualEnergy(int lpc_order,
     shift_norm = 32 - WebRtcSpl_NormW32(word32_high);
     residual_energy = (int32_t)(sum64 >> shift_norm);
   } else {
-    if((word32_low & 0x80000000) == 1) {
+    if((word32_low & 0x80000000) != 0) {
       shift_norm = 1;
-      residual_energy = word32_low >> 1;
+      residual_energy = (uint32_t)word32_low >> 1;
     } else {
       shift_norm = WebRtcSpl_NormW32(word32_low);
       residual_energy = word32_low << shift_norm;
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
index fd45ca3c63..abb87b3c56 100644
--- a/src/modules/audio_coding/codecs/isac/fix/test/isacfix_unittest.cc
+++ b/src/modules/audio_coding/codecs/isac/fix/test/isacfix_unittest.cc
@@ -26,8 +26,29 @@ TEST_F(IsacUnitTest, CalculateResidualEnergyTest) {
   int q_shift_residual = 0;
   int32_t residual_energy = 0;
 
+  // Test the code path where (residual_energy >= 0x10000).
   residual_energy = WebRtcIsacfix_CalculateResidualEnergy(kIntOrder,
       kInt32QDomain, kIntShift, a, corr, &q_shift_residual);
   EXPECT_EQ(1789023310, residual_energy);
   EXPECT_EQ(2, q_shift_residual);
+
+  // Test the code path where (residual_energy < 0x10000)
+  // and ((energy & 0x8000) != 0).
+  for(int i = 0; i < kIntOrder + 1; i++) {
+    a[i] = 24575 >> i;
+    corr[i] = i;
+  }
+  residual_energy = WebRtcIsacfix_CalculateResidualEnergy(kIntOrder,
+      kInt32QDomain, kIntShift, a, corr, &q_shift_residual);
+  EXPECT_EQ(1595279092, residual_energy);
+  EXPECT_EQ(26, q_shift_residual);
+
+  // Test the code path where (residual_energy <= 0x7fff).
+  for(int i = 0; i < kIntOrder + 1; i++) {
+    a[i] = 2457 >> i;
+  }
+  residual_energy = WebRtcIsacfix_CalculateResidualEnergy(kIntOrder,
+      kInt32QDomain, kIntShift, a, corr, &q_shift_residual);
+  EXPECT_EQ(2029266944, residual_energy);
+  EXPECT_EQ(33, q_shift_residual);
 }