diff --git a/src/tests/test_checks.cpp b/src/tests/test_checks_entropy.cpp
similarity index 100%
rename from src/tests/test_checks.cpp
rename to src/tests/test_checks_entropy.cpp
diff --git a/src/tests/test_checks_hex.cpp b/src/tests/test_checks_hex.cpp
new file mode 100644
index 0000000..27c0c6e
--- /dev/null
+++ b/src/tests/test_checks_hex.cpp
@@ -0,0 +1,110 @@
+#include <catch.hpp>
+#include <string>
+#include <vector>
+#include <exception>
+#include "identiconpp.hpp"
+
+using std::string;
+
+class Testiconpp : protected Identiconpp
+{
+public:
+    explicit Testiconpp()
+    : Identiconpp(1, 1) {};
+
+    bool test_check_not_hex(const char &c)
+    {
+        return not_hex(c);
+    }
+};
+
+SCENARIO("Hex checker check", "[checks][hex]")
+{
+    GIVEN("Identiconpp instance")
+    {
+        Testiconpp testicon;
+
+        WHEN("digit is 0-9")
+        {
+            THEN("Return false")
+            {
+                for (char c = 0x30; c <= 0x39; ++c)
+                {
+                    REQUIRE(testicon.test_check_not_hex(c) == false);
+                }
+            }
+        }
+
+        WHEN("digit is A-F")
+        {
+            THEN("Return false")
+            {
+                for (char c = 0x41; c <= 0x46; ++c)
+                {
+                    REQUIRE(testicon.test_check_not_hex(c) == false);
+                }
+            }
+        }
+
+        WHEN("digit is a-f")
+        {
+            THEN("Return false")
+            {
+                for (char c = 0x61; c <= 0x66; ++c)
+                {
+                    REQUIRE(testicon.test_check_not_hex(c) == false);
+                }
+            }
+        }
+
+        WHEN("digit is 0x00 - 0x29")
+        {
+            Testiconpp testicon;
+            THEN("Return true")
+            {
+                for (char c = 0x00; c <= 0x29; ++c)
+                {
+                    REQUIRE(testicon.test_check_not_hex(c));
+                }
+            }
+        }
+
+        WHEN("digit is 0x3a - 0x40")
+        {
+            Testiconpp testicon;
+            THEN("Return true")
+            {
+                for (char c = 0x3a; c <= 0x40; ++c)
+                {
+                    REQUIRE(testicon.test_check_not_hex(c));
+                }
+            }
+        }
+
+        WHEN("digit is 0x47 - 0x60")
+        {
+            Testiconpp testicon;
+            THEN("Return true")
+            {
+                for (char c = 0x47; c <= 0x60; ++c)
+                {
+                    REQUIRE(testicon.test_check_not_hex(c));
+                }
+            }
+        }
+
+        WHEN("digit is 0x67 - 0x7f")
+        {
+            Testiconpp testicon;
+            THEN("Return true")
+            {
+                // We need to use an unsigned char to prevent overflowing
+                for (unsigned char c = 0x67; c <= 0x7f; ++c)
+                {
+                    INFO("c=" << (int)c);
+                    REQUIRE(testicon.test_check_not_hex(c));
+                }
+            }
+        }
+    }
+}