diff --git a/src/addrman.h b/src/addrman.h
index d4f67c2f5b..6347a24d55 100644
--- a/src/addrman.h
+++ b/src/addrman.h
@@ -631,12 +631,12 @@ protected:
     uint256 nKey;
 
     //! Source of random numbers for randomization in inner loops
-    mutable FastRandomContext insecure_rand;
+    mutable FastRandomContext insecure_rand GUARDED_BY(cs);
 
-private:
     //! A mutex to protect the inner data structures.
     mutable Mutex cs;
 
+private:
     //! Serialization versions.
     enum Format : uint8_t {
         V0_HISTORICAL = 0,    //!< historic format, before commit e6b343d88
diff --git a/src/test/addrman_tests.cpp b/src/test/addrman_tests.cpp
index 5e5c5eba69..79c7102c4f 100644
--- a/src/test/addrman_tests.cpp
+++ b/src/test/addrman_tests.cpp
@@ -34,6 +34,7 @@ public:
     //! Ensure that bucket placement is always the same for testing purposes.
     void MakeDeterministic()
     {
+        LOCK(cs);
         nKey.SetNull();
         insecure_rand = FastRandomContext(true);
     }
@@ -87,11 +88,11 @@ public:
     {
         CAddrMan::Clear();
         if (deterministic) {
+            LOCK(cs);
             nKey.SetNull();
             insecure_rand = FastRandomContext(true);
         }
     }
-
 };
 
 static CNetAddr ResolveIP(const std::string& ip)
diff --git a/src/test/fuzz/addrman.cpp b/src/test/fuzz/addrman.cpp
index ee9485eba5..fb003ea3a8 100644
--- a/src/test/fuzz/addrman.cpp
+++ b/src/test/fuzz/addrman.cpp
@@ -27,7 +27,7 @@ class CAddrManDeterministic : public CAddrMan
 public:
     void MakeDeterministic(const uint256& random_seed)
     {
-        insecure_rand = FastRandomContext{random_seed};
+        WITH_LOCK(cs, insecure_rand = FastRandomContext{random_seed});
         Clear();
     }
 };
diff --git a/src/test/net_tests.cpp b/src/test/net_tests.cpp
index 46f88c1282..acbbf357d2 100644
--- a/src/test/net_tests.cpp
+++ b/src/test/net_tests.cpp
@@ -37,6 +37,7 @@ public:
     //! Ensure that bucket placement is always the same for testing purposes.
     void MakeDeterministic()
     {
+        LOCK(cs);
         nKey.SetNull();
         insecure_rand = FastRandomContext(true);
     }