diff --git a/tangem-core/src/main/java/com/tangem/common/extensions/ByteArray.kt b/tangem-core/src/main/java/com/tangem/common/extensions/ByteArray.kt
index ac201f5fcb..226018b9d1 100644
--- a/tangem-core/src/main/java/com/tangem/common/extensions/ByteArray.kt
+++ b/tangem-core/src/main/java/com/tangem/common/extensions/ByteArray.kt
@@ -12,7 +12,7 @@ import kotlin.experimental.xor
  * Extension functions for [ByteArray].
  */
 
-fun ByteArray.toHexString(): String = joinToString("") { "%02x".format(it) }
+fun ByteArray.toHexString(): String = joinToString("") { "%02X".format(it) }
 
 fun ByteArray.toUtf8(): String = String(this).removeSuffix("\u0000")
 
diff --git a/tangem-core/src/test/java/com/tangem/common/extensions/ByteArrayExtensionsTest.kt b/tangem-core/src/test/java/com/tangem/common/extensions/ByteArrayExtensionsTest.kt
index 224144afdb..42cdecc708 100644
--- a/tangem-core/src/test/java/com/tangem/common/extensions/ByteArrayExtensionsTest.kt
+++ b/tangem-core/src/test/java/com/tangem/common/extensions/ByteArrayExtensionsTest.kt
@@ -9,7 +9,7 @@ class ByteArrayExtensionsTest {
 
     @Test
     fun `card Id to Hex String`() {
-        val hex = "cb22000000027374"
+        val hex = "CB22000000027374"
         val bytes = byteArrayOf(-53, 34, 0, 0, 0, 2, 115, 116)
         assertThat(bytes.toHexString())
                 .matches(hex)
diff --git a/tangem-core/src/test/java/com/tangem/common/tlv/TlvDecoderTest.kt b/tangem-core/src/test/java/com/tangem/common/tlv/TlvDecoderTest.kt
index 8f7bd0b91e..d0cc8a62e7 100644
--- a/tangem-core/src/test/java/com/tangem/common/tlv/TlvDecoderTest.kt
+++ b/tangem-core/src/test/java/com/tangem/common/tlv/TlvDecoderTest.kt
@@ -187,6 +187,6 @@ class TlvDecoderTest {
     fun `map Hex returns correct value`() {
         val cardId: String = tlvMapper.decode(TlvTag.CardId)
         assertThat(cardId)
-                .isEqualTo("cb22000000027374")
+                .isEqualTo("CB22000000027374")
     }
 }
\ No newline at end of file