diff --git a/src/test/miniscript_tests.cpp b/src/test/miniscript_tests.cpp
index f253562a2f6..c2b0d43dccf 100644
--- a/src/test/miniscript_tests.cpp
+++ b/src/test/miniscript_tests.cpp
@@ -298,7 +298,7 @@ using Node = miniscript::Node<CPubKey>;
 
 /** Compute all challenges (pubkeys, hashes, timelocks) that occur in a given Miniscript. */
 // NOLINTNEXTLINE(misc-no-recursion)
-std::set<Challenge> FindChallenges(const NodeRef& ref) {
+std::set<Challenge> FindChallenges_recursive(const NodeRef& ref) {
     std::set<Challenge> chal;
     for (const auto& key : ref->keys) {
         chal.emplace(ChallengeType::PK, ChallengeNumber(key));
@@ -317,12 +317,44 @@ std::set<Challenge> FindChallenges(const NodeRef& ref) {
         chal.emplace(ChallengeType::HASH160, ChallengeNumber(ref->data));
     }
     for (const auto& sub : ref->subs) {
-        auto sub_chal = FindChallenges(sub);
+        auto sub_chal = FindChallenges_recursive(sub);
         chal.insert(sub_chal.begin(), sub_chal.end());
     }
     return chal;
 }
 
+/** Compute all challenges (pubkeys, hashes, timelocks) that occur in a given Miniscript. */
+std::set<Challenge> FindChallenges(const NodeRef& root)
+{
+    std::set<Challenge> chal;
+
+    for (std::vector stack{root.get()}; !stack.empty();) {
+        const Node* ref{stack.back()};
+        stack.pop_back();
+
+        for (const auto& key : ref->keys) {
+            chal.emplace(ChallengeType::PK, ChallengeNumber(key));
+        }
+        if (ref->fragment == miniscript::Fragment::OLDER) {
+            chal.emplace(ChallengeType::OLDER, ref->k);
+        } else if (ref->fragment == miniscript::Fragment::AFTER) {
+            chal.emplace(ChallengeType::AFTER, ref->k);
+        } else if (ref->fragment == miniscript::Fragment::SHA256) {
+            chal.emplace(ChallengeType::SHA256, ChallengeNumber(ref->data));
+        } else if (ref->fragment == miniscript::Fragment::RIPEMD160) {
+            chal.emplace(ChallengeType::RIPEMD160, ChallengeNumber(ref->data));
+        } else if (ref->fragment == miniscript::Fragment::HASH256) {
+            chal.emplace(ChallengeType::HASH256, ChallengeNumber(ref->data));
+        } else if (ref->fragment == miniscript::Fragment::HASH160) {
+            chal.emplace(ChallengeType::HASH160, ChallengeNumber(ref->data));
+        }
+        for (const auto& sub : ref->subs) {
+            stack.push_back(sub.get());
+        }
+    }
+    return chal;
+}
+
 //! The spk for this script under the given context. If it's a Taproot output also record the spend data.
 CScript ScriptPubKey(miniscript::MiniscriptContext ctx, const CScript& script, TaprootBuilder& builder)
 {
@@ -347,7 +379,9 @@ struct MiniScriptTest : BasicTestingSetup {
 /** Run random satisfaction tests. */
 void TestSatisfy(const KeyConverter& converter, const std::string& testcase, const NodeRef& node) {
     auto script = node->ToScript(converter);
-    auto challenges = FindChallenges(node); // Find all challenges in the generated miniscript.
+    const auto challenges_recursive{FindChallenges_recursive(node)};
+    const auto challenges{FindChallenges(node)}; // Find all challenges in the generated miniscript.
+    BOOST_CHECK(challenges_recursive == challenges);
     std::vector<Challenge> challist(challenges.begin(), challenges.end());
     for (int iter = 0; iter < 3; ++iter) {
         std::shuffle(challist.begin(), challist.end(), m_rng);