diff --git a/lib/asn1.js b/lib/asn1.js
index e3cb5007b..7a2d2d4ab 100644
--- a/lib/asn1.js
+++ b/lib/asn1.js
@@ -778,17 +778,18 @@ asn1.oidToDer = function(oid) {
   var values = oid.split('.');
   var bytes = forge.util.createBuffer();
 
-  // first byte is 40 * value1 + value2
-  bytes.putByte(40 * parseInt(values[0], 10) + parseInt(values[1], 10));
-  // other bytes are each value in base 128 with 8th bit set except for
-  // the last byte for each value
+  // the first subidentifier is 40 * value1 + value2; the remaining
+  // subidentifiers are each a single value. every subidentifier is encoded in
+  // base 128 with the 8th bit set on every byte except its last.
   var last, valueBytes, value, b;
-  for(var i = 2; i < values.length; ++i) {
+  for(var i = 1; i < values.length; ++i) {
     // produce value bytes in reverse because we don't know how many
     // bytes it will take to store the value
     last = true;
     valueBytes = [];
-    value = parseInt(values[i], 10);
+    value = (i === 1) ?
+      40 * parseInt(values[0], 10) + parseInt(values[1], 10) :
+      parseInt(values[i], 10);
     // TODO: Change bitwise logic to allow larger values.
     if(value > 0xffffffff) {
       throw new Error('OID value too large; max is 32-bits.');
@@ -830,13 +831,12 @@ asn1.derToOid = function(bytes) {
     bytes = forge.util.createBuffer(bytes);
   }
 
-  // first byte is 40 * value1 + value2
-  var b = bytes.getByte();
-  oid = Math.floor(b / 40) + '.' + (b % 40);
-
-  // other bytes are each value in base 128 with 8th bit set except for
-  // the last byte for each value
+  // each subidentifier is encoded in base 128 with the 8th bit set on every
+  // byte except its last; the first subidentifier encodes the first two arcs
+  // as 40 * value1 + value2.
+  var b;
   var value = 0;
+  var first = true;
   while(bytes.length() > 0) {
     // error if 7b shift would exceed Number.MAX_SAFE_INTEGER
     // (Number.MAX_SAFE_INTEGER / 128)
@@ -850,7 +850,16 @@ asn1.derToOid = function(bytes) {
       value += b & 0x7F;
     } else {
       // last byte
-      oid += '.' + (value + b);
+      value += b;
+      if(first) {
+        // split the first subidentifier into the first two arcs
+        oid = (value < 80) ?
+          Math.floor(value / 40) + '.' + (value % 40) :
+          '2.' + (value - 80);
+        first = false;
+      } else {
+        oid += '.' + value;
+      }
       value = 0;
     }
   }
diff --git a/tests/unit/asn1.js b/tests/unit/asn1.js
index a99783cb9..4e8a6906e 100644
--- a/tests/unit/asn1.js
+++ b/tests/unit/asn1.js
@@ -54,6 +54,18 @@ var UTIL = require('../../lib/util');
       );
     });
 
+    it('should convert an OID with a multi-byte first subidentifier to DER', function() {
+      // X.690 8.19: the first subidentifier (40 * arc1 + arc2) can exceed one
+      // byte when arc1 is 2, so it must be encoded in base 128
+      ASSERT.equal(ASN1.oidToDer('2.999.3').toHex(), '883703');
+      ASSERT.equal(ASN1.oidToDer('2.100').toHex(), '8134');
+    });
+
+    it('should convert an OID with a multi-byte first subidentifier from DER', function() {
+      ASSERT.equal(ASN1.derToOid(UTIL.hexToBytes('883703')), '2.999.3');
+      ASSERT.equal(ASN1.derToOid(UTIL.hexToBytes('8134')), '2.100');
+    });
+
     it('should convert INTEGER 0 to DER', function() {
       ASSERT.equal(ASN1.integerToDer(0).toHex(), '00');
     });