diff --git a/docs/changelog.md b/docs/changelog.md
index c1104f470..c249be473 100644
--- a/docs/changelog.md
+++ b/docs/changelog.md
@@ -19,6 +19,10 @@ SPDX-FileCopyrightText: 2011-2020 Carles Fernandez-Prades <carles.fernandez@cttc
 
 - The software can now be cross-compiled on Petalinux environments.   
 
+### Improvements in Reliability:
+
+- Fixed a bug in GLONASS GNAV CRC computation.
+
 ### Improvements in Reproducibility:
 
 - Improved reproducibility of the volk_gnsssdr library: Drop compile-time CPU
diff --git a/src/core/system_parameters/glonass_gnav_navigation_message.cc b/src/core/system_parameters/glonass_gnav_navigation_message.cc
index 63ac60479..91209110c 100644
--- a/src/core/system_parameters/glonass_gnav_navigation_message.cc
+++ b/src/core/system_parameters/glonass_gnav_navigation_message.cc
@@ -194,8 +194,8 @@ bool Glonass_Gnav_Navigation_Message::CRC_test(std::bitset<GLONASS_GNAV_STRING_B
         {
             return true;
         }
-    // (a-ii) Only one of the checksums (C1,...,C7) is equal to zero but C_Sigma = 1
-    if (C_Sigma == 1 && C1 + C2 + C3 + C4 + C5 + C6 + C7 == 6)
+    // (a-ii) Only one of the checksums (C1,...,C7) is equal to 1 and C_Sigma = 1
+    if (C_Sigma == 1 && C1 + C2 + C3 + C4 + C5 + C6 + C7 == 1)
         {
             return true;
         }
diff --git a/src/tests/test_main.cc b/src/tests/test_main.cc
index ec19fcbbf..3d54ce6bd 100644
--- a/src/tests/test_main.cc
+++ b/src/tests/test_main.cc
@@ -118,6 +118,7 @@ DECLARE_string(log_dir);
 #include "unit-tests/signal-processing-blocks/pvt/rtcm_test.cc"
 #include "unit-tests/signal-processing-blocks/pvt/serdes_monitor_pvt_test.cc"
 #include "unit-tests/signal-processing-blocks/telemetry_decoder/galileo_fnav_inav_decoder_test.cc"
+#include "unit-tests/system-parameters/glonass_gnav_crc_test.cc"
 #include "unit-tests/system-parameters/glonass_gnav_ephemeris_test.cc"
 #include "unit-tests/system-parameters/glonass_gnav_nav_message_test.cc"
 
diff --git a/src/tests/unit-tests/system-parameters/glonass_gnav_crc_test.cc b/src/tests/unit-tests/system-parameters/glonass_gnav_crc_test.cc
new file mode 100644
index 000000000..e0ef6691d
--- /dev/null
+++ b/src/tests/unit-tests/system-parameters/glonass_gnav_crc_test.cc
@@ -0,0 +1,40 @@
+/*!
+ * \file glonass_gnav_crc_test.cc
+ * \brief Test fot GLONASS GNAV CRC
+ * \author Carles Fernandez-Prades, 2020. cfernandez(at)cttc.es
+ *
+ *
+ * -------------------------------------------------------------------------
+ *
+ * Copyright (C) 2020  (see AUTHORS file for a list of contributors)
+ *
+ * GNSS-SDR is a software defined Global Navigation
+ *          Satellite Systems receiver
+ *
+ * This file is part of GNSS-SDR.
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ *
+ * -------------------------------------------------------------------------
+ */
+
+#include "glonass_gnav_navigation_message.h"
+#include <bitset>
+#include <string>
+
+TEST(GlonassCrcTest, GnssSdrCRCTest)
+{
+    // test data
+    std::string string1Real_14_18_00("0000100000111001001001000011101010101100010101001000001001011101010101110011110110101");
+    std::string string1Real_14_18_30("0000100000111001001011000011101010101100010101001000001001011101010101110011100001010");
+    std::string string1Wrong_14_18_00("0000100000111001001001000011101010101100010101001000001001011101010101110011100001010");
+
+    auto gnav_msg = Glonass_Gnav_Navigation_Message();
+    std::bitset<GLONASS_GNAV_STRING_BITS> bits;
+    bits = std::bitset<GLONASS_GNAV_STRING_BITS>(string1Real_14_18_00);
+    ASSERT_TRUE(gnav_msg.CRC_test(bits));
+    bits = std::bitset<GLONASS_GNAV_STRING_BITS>(string1Real_14_18_30);
+    ASSERT_TRUE(gnav_msg.CRC_test(bits));
+    bits = std::bitset<GLONASS_GNAV_STRING_BITS>(string1Wrong_14_18_00);
+    ASSERT_FALSE(gnav_msg.CRC_test(bits));
+}