diff --git a/lib/buffer.js b/lib/buffer.js
index cdc0f4b0a53..2e1d6a045db 100644
--- a/lib/buffer.js
+++ b/lib/buffer.js
@@ -84,7 +84,7 @@ SlowBuffer.prototype.toString = function(encoding, start, end) {
       return this.ucs2Slice(start, end);
 
     default:
-      throw new Error('Unknown encoding');
+      throw new Error('Unknown encoding: ' + encoding);
   }
 };
 
@@ -170,7 +170,7 @@ SlowBuffer.prototype.write = function(string, offset, length, encoding) {
       return this.ucs2Write(string, offset, length);
 
     default:
-      throw new Error('Unknown encoding');
+      throw new Error('Unknown encoding: ' + encoding);
   }
 };
 
@@ -402,7 +402,7 @@ Buffer.prototype.write = function(string, offset, length, encoding) {
       break;
 
     default:
-      throw new Error('Unknown encoding');
+      throw new Error('Unknown encoding: ' + encoding);
   }
 
   Buffer._charsWritten = SlowBuffer._charsWritten;
@@ -459,7 +459,7 @@ Buffer.prototype.toString = function(encoding, start, end) {
       return this.parent.ucs2Slice(start, end);
 
     default:
-      throw new Error('Unknown encoding');
+      throw new Error('Unknown encoding: ' + encoding);
   }
 };
 
diff --git a/test/simple/test-buffer.js b/test/simple/test-buffer.js
index c6d2a9ff2df..7f263af44e2 100644
--- a/test/simple/test-buffer.js
+++ b/test/simple/test-buffer.js
@@ -125,6 +125,24 @@ try {
 }
 assert.strictEqual('sourceStart out of bounds', caught_error.message);
 
+// invalid encoding for Buffer.toString
+caught_error = null;
+try {
+  var copied = b.toString('invalid');
+} catch (err) {
+  caught_error = err;
+}
+assert.strictEqual('Unknown encoding: invalid', caught_error.message);
+
+// invalid encoding for Buffer.write
+caught_error = null;
+try {
+  var copied = b.write('test string', 0, 5, 'invalid');
+} catch (err) {
+  caught_error = err;
+}
+assert.strictEqual('Unknown encoding: invalid', caught_error.message);
+
 // a too-low sourceEnd will get caught by earlier checks
 
 // try to copy ending after the end of b
@@ -600,6 +618,24 @@ assert.equal(0xad, b[1]);
 assert.equal(0xbe, b[2]);
 assert.equal(0xef, b[3]);
 
+// testing invalid encoding on SlowBuffer.toString
+caught_error = null;
+try {
+  var copied = b.toString('invalid');
+} catch (err) {
+  caught_error = err;
+}
+assert.strictEqual('Unknown encoding: invalid', caught_error.message);
+
+// testing invalid encoding on SlowBuffer.write
+caught_error = null;
+try {
+  var copied = b.write('some string', 0, 5, 'invalid');
+} catch (err) {
+  caught_error = err;
+}
+assert.strictEqual('Unknown encoding: invalid', caught_error.message);
+
 
 // This should not segfault the program.
 assert.throws(function() {