diff --git a/lib/coins/coinentry.js b/lib/coins/coinentry.js
index 05ca7d0f..512cd9b1 100644
--- a/lib/coins/coinentry.js
+++ b/lib/coins/coinentry.js
@@ -14,6 +14,13 @@ const StaticWriter = require('../utils/staticwriter');
 const encoding = require('../utils/encoding');
 const compress = require('./compress');
 
+/*
+ * Constants
+ */
+
+const NUM_FLAGS = 3;
+const MAX_HEIGHT = ((1 << (32 - NUM_FLAGS)) >>> 0) - 1;
+
 /**
  * Represents an unspent output.
  * @alias module:coins.CoinEntry
@@ -171,17 +178,15 @@ CoinEntry.prototype.toWriter = function toWriter(bw) {
   }
 
   let height = this.height;
-  let flags = 0;
-
-  // We save 29 bits for the height.
-  // This should be good for the next 4000 years.
-  if (height === -1)
-    height = 0x1fffffff;
+  let field = 0;
 
   if (this.coinbase)
-    flags |= 1;
+    field |= 1;
 
-  const field = (height * 8) | flags;
+  if (height === -1)
+    height = MAX_HEIGHT;
+
+  field |= height << NUM_FLAGS;
 
   bw.writeVarint(this.version);
   bw.writeU32(field);
@@ -219,14 +224,13 @@ CoinEntry.prototype.fromReader = function fromReader(br) {
   const version = br.readVarint();
   const field = br.readU32();
 
-  const flags = field & 0x07;
-  let height = field / 8 | 0;
+  let height = field >>> NUM_FLAGS;
 
-  if (height === 0x1fffffff)
+  if (height === MAX_HEIGHT)
     height = -1;
 
   this.version = version;
-  this.coinbase = (flags & 1) !== 0;
+  this.coinbase = (field & 1) !== 0;
   this.height = height;
 
   compress.unpack(this.output, br);