diff --git a/lib/services/db.js b/lib/services/db.js
index 6e4f8b93..faf42c8b 100644
--- a/lib/services/db.js
+++ b/lib/services/db.js
@@ -209,9 +209,16 @@ DB.prototype.getBlockHashesByTimestamp = function(high, low, callback) {
   var self = this;
   var hashes = [];
 
+  try {
+    var lowKey = this._encodeBlockIndexKey(low);
+    var highKey = this._encodeBlockIndexKey(high);
+  } catch(e) {
+    return callback(e);
+  }
+
   var stream = this.store.createReadStream({
-    gte: this._encodeBlockIndexKey(low),
-    lte: this._encodeBlockIndexKey(high),
+    gte: lowKey,
+    lte: highKey,
     reverse: true,
     valueEncoding: 'binary',
     keyEncoding: 'binary'
@@ -456,6 +463,7 @@ DB.prototype.runAllBlockHandlers = function(block, add, callback) {
 };
 
 DB.prototype._encodeBlockIndexKey = function(timestamp) {
+  $.checkArgument(timestamp >= 0 && timestamp <= 4294967295, 'timestamp out of bounds');
   var timestampBuffer = new Buffer(4);
   timestampBuffer.writeUInt32BE(timestamp);
   return Buffer.concat([DB.PREFIXES.BLOCKS, timestampBuffer]);
diff --git a/test/services/db.unit.js b/test/services/db.unit.js
index 82148b5d..c3106145 100644
--- a/test/services/db.unit.js
+++ b/test/services/db.unit.js
@@ -423,6 +423,20 @@ describe('DB Service', function() {
 
       readStream.emit('close');
     });
+
+    it('should give an error if the timestamp is out of range', function(done) {
+      var db = new DB(baseConfig);
+      var readStream = new EventEmitter();
+      db.store = {
+        createReadStream: sinon.stub().returns(readStream)
+      };
+
+      db.getBlockHashesByTimestamp(-1, -5, function(err, hashes) {
+        should.exist(err);
+        err.message.should.equal('Invalid Argument: timestamp out of bounds');
+        done();
+      });
+    });
   });
 
   describe('#getPrevHash', function() {