diff --git a/src/test/fuzz/asmap_direct.cpp b/src/test/fuzz/asmap_direct.cpp
index 2dcfb6054..f8a8dd94a 100644
--- a/src/test/fuzz/asmap_direct.cpp
+++ b/src/test/fuzz/asmap_direct.cpp
@@ -1,61 +1,61 @@
 // Copyright (c) 2020 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include <util/asmap.h>
 
 #include <test/fuzz/fuzz.h>
 
 #include <cassert>
 #include <cstdint>
+#include <optional>
 #include <vector>
 
 void test_one_input(const std::vector<uint8_t> &buffer) {
     // Encoding: [asmap using 1 bit / byte] 0xFF [addr using 1 bit / byte]
-    bool have_sep = false;
-    size_t sep_pos;
+    std::optional<size_t> sep_pos_opt;
     for (size_t pos = 0; pos < buffer.size(); ++pos) {
         uint8_t x = buffer[pos];
         if ((x & 0xFE) == 0) {
             continue;
         }
         if (x == 0xFF) {
-            if (have_sep) {
+            if (sep_pos_opt) {
                 return;
             }
-            have_sep = true;
-            sep_pos = pos;
+            sep_pos_opt = pos;
         } else {
             return;
         }
     }
-    if (!have_sep) {
+    if (!sep_pos_opt) {
         // Needs exactly 1 separator
         return;
     }
+    const size_t sep_pos{sep_pos_opt.value()};
     if (buffer.size() - sep_pos - 1 > 128) {
         // At most 128 bits in IP address
         return;
     }
 
     // Checks on asmap
     std::vector<bool> asmap(buffer.begin(), buffer.begin() + sep_pos);
     if (SanityCheckASMap(asmap, buffer.size() - 1 - sep_pos)) {
         // Verify that for valid asmaps, no prefix (except up to 7 zero padding
         // bits) is valid.
         std::vector<bool> asmap_prefix = asmap;
         while (!asmap_prefix.empty() &&
                asmap_prefix.size() + 7 > asmap.size() &&
                asmap_prefix.back() == false) {
             asmap_prefix.pop_back();
         }
         while (!asmap_prefix.empty()) {
             asmap_prefix.pop_back();
             assert(
                 !SanityCheckASMap(asmap_prefix, buffer.size() - 1 - sep_pos));
         }
         // No address input should trigger assertions in interpreter
         std::vector<bool> addr(buffer.begin() + sep_pos + 1, buffer.end());
         (void)Interpret(asmap, addr);
     }
 }