diff --git a/ChangeLog b/ChangeLog
index bc42246..9ab0c03 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -7,6 +7,7 @@
      rfc 5280 section 4.2.1.4.
    * It is now possible to use NIST key wrap mode via the mbedtls_cipher API.
      Contributed by Jack Lloyd and Fortanix Inc.
+   * Add the Wi-SUN Field Area Network (FAN) device extended key usage.
 
 Bugfix
    * Fix private key DER output in the key_app_writer example. File contents
diff --git a/include/mbedtls/oid.h b/include/mbedtls/oid.h
index 342ef75..55f72c8 100644
--- a/include/mbedtls/oid.h
+++ b/include/mbedtls/oid.h
@@ -122,7 +122,8 @@
  * { iso(1) identified-organization(3) dod(6) internet(1)
  *                      security(5) mechanisms(5) pkix(7) }
  */
-#define MBEDTLS_OID_PKIX                        MBEDTLS_OID_ISO_IDENTIFIED_ORG MBEDTLS_OID_ORG_DOD "\x01\x05\x05\x07"
+#define MBEDTLS_OID_INTERNET                    MBEDTLS_OID_ISO_IDENTIFIED_ORG MBEDTLS_OID_ORG_DOD "\x01"
+#define MBEDTLS_OID_PKIX                        MBEDTLS_OID_INTERNET "\x05\x05\x07"
 
 /*
  * Arc for standard naming attributes
@@ -206,6 +207,13 @@
 #define MBEDTLS_OID_TIME_STAMPING               MBEDTLS_OID_KP "\x08" /**< id-kp-timeStamping OBJECT IDENTIFIER ::= { id-kp 8 } */
 #define MBEDTLS_OID_OCSP_SIGNING                MBEDTLS_OID_KP "\x09" /**< id-kp-OCSPSigning OBJECT IDENTIFIER ::= { id-kp 9 } */
 
+/**
+ * Wi-SUN Alliance Field Area Network
+ * { iso(1) identified-organization(3) dod(6) internet(1)
+ *                      private(4) enterprise(1) WiSUN(45605) FieldAreaNetwork(1) }
+ */
+#define MBEDTLS_OID_WISUN_FAN                  MBEDTLS_OID_INTERNET "\x04\x01\x82\xe4\x25\x01"
+
 /*
  * PKCS definition OIDs
  */
diff --git a/library/oid.c b/library/oid.c
index 4e10f8a..8059a33 100644
--- a/library/oid.c
+++ b/library/oid.c
@@ -284,12 +284,13 @@
 
 static const mbedtls_oid_descriptor_t oid_ext_key_usage[] =
 {
-    { ADD_LEN( MBEDTLS_OID_SERVER_AUTH ),      "id-kp-serverAuth",      "TLS Web Server Authentication" },
-    { ADD_LEN( MBEDTLS_OID_CLIENT_AUTH ),      "id-kp-clientAuth",      "TLS Web Client Authentication" },
-    { ADD_LEN( MBEDTLS_OID_CODE_SIGNING ),     "id-kp-codeSigning",     "Code Signing" },
-    { ADD_LEN( MBEDTLS_OID_EMAIL_PROTECTION ), "id-kp-emailProtection", "E-mail Protection" },
-    { ADD_LEN( MBEDTLS_OID_TIME_STAMPING ),    "id-kp-timeStamping",    "Time Stamping" },
-    { ADD_LEN( MBEDTLS_OID_OCSP_SIGNING ),     "id-kp-OCSPSigning",     "OCSP Signing" },
+    { ADD_LEN( MBEDTLS_OID_SERVER_AUTH ),      "id-kp-serverAuth",       "TLS Web Server Authentication" },
+    { ADD_LEN( MBEDTLS_OID_CLIENT_AUTH ),      "id-kp-clientAuth",       "TLS Web Client Authentication" },
+    { ADD_LEN( MBEDTLS_OID_CODE_SIGNING ),     "id-kp-codeSigning",      "Code Signing" },
+    { ADD_LEN( MBEDTLS_OID_EMAIL_PROTECTION ), "id-kp-emailProtection",  "E-mail Protection" },
+    { ADD_LEN( MBEDTLS_OID_TIME_STAMPING ),    "id-kp-timeStamping",     "Time Stamping" },
+    { ADD_LEN( MBEDTLS_OID_OCSP_SIGNING ),     "id-kp-OCSPSigning",      "OCSP Signing" },
+    { ADD_LEN( MBEDTLS_OID_WISUN_FAN ),        "id-kp-wisun-fan-device", "Wi-SUN Alliance Field Area Network (FAN)" },
     { NULL, 0, NULL, NULL },
 };
 
diff --git a/tests/suites/test_suite_oid.data b/tests/suites/test_suite_oid.data
index 759a010..625085f 100644
--- a/tests/suites/test_suite_oid.data
+++ b/tests/suites/test_suite_oid.data
@@ -6,3 +6,30 @@
 
 OID get certificate policy wrong oid - id-ce-authorityKeyIdentifier
 oid_get_certificate_policies:"551D23":""
+
+OID get Ext Key Usage - id-kp-serverAuth
+oid_get_extended_key_usage:"2B06010505070301":"TLS Web Server Authentication"
+
+OID get Ext Key Usage - id-kp-clientAuth
+oid_get_extended_key_usage:"2B06010505070302":"TLS Web Client Authentication"
+
+OID get Ext Key Usage - id-kp-codeSigning
+oid_get_extended_key_usage:"2B06010505070303":"Code Signing"
+
+OID get Ext Key Usage - id-kp-emailProtection
+oid_get_extended_key_usage:"2B06010505070304":"E-mail Protection"
+
+OID get Ext Key Usage - id-kp-timeStamping
+oid_get_extended_key_usage:"2B06010505070308":"Time Stamping"
+
+OID get Ext Key Usage - id-kp-OCSPSigning
+oid_get_extended_key_usage:"2B06010505070309":"OCSP Signing"
+
+OID get Ext Key Usage - id-kp-wisun-fan-device
+oid_get_extended_key_usage:"2B0601040182E42501":"Wi-SUN Alliance Field Area Network (FAN)"
+
+OID get Ext Key Usage invalid oid
+oid_get_extended_key_usage:"5533445566":""
+
+OID get Ext Key Usage wrong oid - id-ce-authorityKeyIdentifier
+oid_get_extended_key_usage:"551D23":""
diff --git a/tests/suites/test_suite_oid.function b/tests/suites/test_suite_oid.function
index e95e48d..59e700e 100644
--- a/tests/suites/test_suite_oid.function
+++ b/tests/suites/test_suite_oid.function
@@ -32,3 +32,26 @@
     }
 }
 /* END_CASE */
+
+/* BEGIN_CASE */
+void oid_get_extended_key_usage( data_t *oid, char *result_str )
+{
+    mbedtls_asn1_buf asn1_buf = { 0, 0, NULL };
+    int ret;
+    const char *desc;
+
+    asn1_buf.tag = MBEDTLS_ASN1_OID;
+    asn1_buf.p = oid->x;
+    asn1_buf.len = oid->len;
+
+    ret = mbedtls_oid_get_extended_key_usage( &asn1_buf, &desc );
+    if( strlen( result_str ) == 0 )
+    {
+        TEST_ASSERT( ret == MBEDTLS_ERR_OID_NOT_FOUND );
+    }
+    else
+    {
+        TEST_ASSERT( strcmp( ( char * )desc, result_str ) == 0 );
+    }
+}
+/* END_CASE */