diff --git a/test/lazy-proof-dependencies.test.js b/test/lazy-proof-dependencies.test.js
new file mode 100644
index 0000000..76476d5
--- /dev/null
+++ b/test/lazy-proof-dependencies.test.js
@@ -0,0 +1,124 @@
+const test = require('tape')
+const { spawnSync } = require('node:child_process')
+const path = require('node:path')
+
+function runIsolated (t, source) {
+  const child = spawnSync(process.execPath, [
+    '--unhandled-rejections=strict', '-e', source, require.resolve('..')
+  ], {
+    cwd: path.resolve(__dirname, '..'),
+    encoding: 'utf8',
+    timeout: 10000
+  })
+  t.error(child.error, 'isolated process completes')
+  t.equal(child.status, 0, child.stderr || 'isolated assertions pass')
+  t.end()
+}
+
+test('ordinary imports tolerate unavailable proof dependencies until proof use', t => {
+  runIsolated(t, `
+    const assert = require('node:assert/strict')
+    const Module = require('node:module')
+    const load = Module._load
+    const failure = new Error('proof dependency unavailable')
+    const requests = []
+    const proofPackages = new Set([
+      'eth-proof', 'eth-util-lite', 'eth-object',
+      'merkle-patricia-tree', 'ethereumjs-util', 'elliptic'
+    ])
+    Module._load = function (request) {
+      if (proofPackages.has(request)) {
+        requests.push(request)
+        throw failure
+      }
+      return load.apply(this, arguments)
+    }
+    const library = require(process.argv[1])
+    assert.equal(typeof library.utils.HDSigner, 'function')
+    assert.equal(typeof library.utils.buildEthProof, 'function')
+    assert.equal(typeof library.SyscoinJSLib.prototype.assetAllocationMint, 'function')
+    assert.deepEqual(requests, [])
+    ;(async () => {
+      await assert.rejects(library.utils.buildEthProof({}), error => error === failure)
+      assert.deepEqual(requests, ['eth-proof'])
+    })().catch(error => { console.error(error); process.exitCode = 1 })
+  `)
+})
+
+test('first proof use loads its dependencies and preserves constructor rejection', t => {
+  runIsolated(t, `
+    const assert = require('node:assert/strict')
+    const Module = require('node:module')
+    const load = Module._load
+    const requests = []
+    const failure = new Error('proof constructor failure')
+    const endpoint = 'http://127.0.0.1:1'
+    let constructions = 0
+    const replacements = {
+      'eth-proof': {
+        VerifyProof: {},
+        GetProof: class {
+          constructor (url) {
+            assert.equal(url, endpoint)
+            constructions++
+            throw failure
+          }
+        }
+      },
+      'eth-util-lite': { encode () {} },
+      'eth-object': { Log: {} }
+    }
+    Module._load = function (request) {
+      if (Object.hasOwn(replacements, request)) {
+        requests.push(request)
+        return replacements[request]
+      }
+      return load.apply(this, arguments)
+    }
+    const library = require(process.argv[1])
+    assert.deepEqual(requests, [])
+    ;(async () => {
+      await assert.rejects(library.utils.buildEthProof({ web3url: endpoint }), error => error === failure)
+      assert.deepEqual(requests, ['eth-proof', 'eth-util-lite', 'eth-object'])
+      assert.equal(constructions, 1)
+    })().catch(error => { console.error(error); process.exitCode = 1 })
+  `)
+})
+
+test('proof execution failures retain the existing returned-error behavior', t => {
+  runIsolated(t, `
+    const assert = require('node:assert/strict')
+    const Module = require('node:module')
+    const load = Module._load
+    const failure = new Error('proof request failure')
+    const txid = '0x' + '11'.repeat(32)
+    let requests = 0
+    const replacements = {
+      'eth-proof': {
+        VerifyProof: {},
+        GetProof: class {
+          async transactionProof (hash) {
+            assert.equal(hash, txid)
+            requests++
+            throw failure
+          }
+        }
+      },
+      'eth-util-lite': { encode () {} },
+      'eth-object': { Log: {} }
+    }
+    Module._load = function (request) {
+      if (Object.hasOwn(replacements, request)) return replacements[request]
+      return load.apply(this, arguments)
+    }
+    const library = require(process.argv[1])
+    const messages = []
+    console.log = message => messages.push(message)
+    ;(async () => {
+      const result = await library.utils.buildEthProof({ web3url: 'http://127.0.0.1:1', ethtxid: txid })
+      assert.equal(result, failure)
+      assert.equal(requests, 1)
+      assert.deepEqual(messages, ['Exception: proof request failure'])
+    })().catch(error => { console.error(error); process.exitCode = 1 })
+  `)
+})
diff --git a/utils.js b/utils.js
index df13d88..a761523 100644
--- a/utils.js
+++ b/utils.js
@@ -23,9 +23,6 @@ bjs.ECPair = ECPair
 bjs.bip32 = bip32
 const bitcoinops = require('bitcoin-ops')
 const varuint = require('varuint-bitcoin')
-const { VerifyProof, GetProof } = require('eth-proof')
-const { encode } = require('eth-util-lite')
-const { Log } = require('eth-object')
 const { AbiCoder } = require('ethers/abi')
 const { keccak256 } = require('ethers/crypto')
 const { JsonRpcProvider } = require('ethers/providers')
@@ -1042,6 +1039,9 @@ Param assetOpts: Required. Object containing web3url and ethtxid fields populate
 Returns: Returns JSON object in response, SPV proof object in JSON
 */
 async function buildEthProof (assetOpts) {
+  const { VerifyProof, GetProof } = require('eth-proof')
+  const { encode } = require('eth-util-lite')
+  const { Log } = require('eth-object')
   const ethProof = new GetProof(assetOpts.web3url)
   const web3Provider = new JsonRpcProvider(assetOpts.web3url)
   try {