diff --git a/src/Notifier.h b/src/Notifier.h
index 592c491219..6da7d7c59f 100644
--- a/src/Notifier.h
+++ b/src/Notifier.h
@@ -99,6 +99,8 @@ extern Registry registry;
  */
 class Modifiable {
 public:
+    virtual ~Modifiable();
+
     /**
      * Calling this method signals to all registered receivers that the
      * object has been modified.
@@ -111,8 +113,6 @@ public:
 protected:
     friend class Registry;
 
-    virtual ~Modifiable();
-
     // Number of currently registered receivers.
     uint64_t num_receivers = 0;
 };
diff --git a/src/Stmt.h b/src/Stmt.h
index cc242170d7..a0870c2896 100644
--- a/src/Stmt.h
+++ b/src/Stmt.h
@@ -21,6 +21,8 @@ class ZAMCompiler; // for "friend" declarations
 
 class ExprListStmt : public Stmt {
 public:
+    ~ExprListStmt() override;
+
     const ListExpr* ExprList() const { return l.get(); }
     const ListExprPtr& ExprListPtr() const { return l; }
 
@@ -35,8 +37,6 @@ public:
 protected:
     ExprListStmt(StmtTag t, ListExprPtr arg_l);
 
-    ~ExprListStmt() override;
-
     ValPtr Exec(Frame* f, StmtFlowType& flow) override;
     virtual ValPtr DoExec(std::vector<ValPtr> vals, StmtFlowType& flow) = 0;
 
diff --git a/src/Type.h b/src/Type.h
index d1d01b55c7..e17de61cc2 100644
--- a/src/Type.h
+++ b/src/Type.h
@@ -356,6 +356,8 @@ protected:
 
 class IndexType : public Type {
 public:
+    ~IndexType() override = default;
+
     int MatchesIndex(detail::ListExpr* index) const override;
 
     const TypeListPtr& GetIndices() const { return indices; }
@@ -391,8 +393,6 @@ protected:
         is_pattern_index = types.size() == 1 && types[0]->Tag() == TYPE_PATTERN;
     }
 
-    ~IndexType() override = default;
-
     void DoDescribe(ODesc* d) const override;
 
     TypeListPtr indices;
diff --git a/src/script_opt/CPP/RuntimeInits.h b/src/script_opt/CPP/RuntimeInits.h
index e582f0f492..c1fa9f87da 100644
--- a/src/script_opt/CPP/RuntimeInits.h
+++ b/src/script_opt/CPP/RuntimeInits.h
@@ -327,6 +327,8 @@ public:
         inits_vec.resize(inits.size());
     }
 
+    virtual ~CPP_AbstractBasicConsts() = default;
+
     void InitializeCohort(InitsManager* im, int cohort) {
         ASSERT(cohort == 0);
         auto& offsets_vec = im->Indices(offsets_set);
diff --git a/src/spicy/file-analyzer.h b/src/spicy/file-analyzer.h
index 0395c4b9f4..ad4bba6d86 100644
--- a/src/spicy/file-analyzer.h
+++ b/src/spicy/file-analyzer.h
@@ -25,6 +25,8 @@ public:
      */
     FileState(Cookie cookie) : ParsingState(::spicy::rt::driver::ParsingType::Stream), _cookie(std::move(cookie)) {}
 
+    virtual ~FileState() = default;
+
     /** Returns the cookie pointer to use with the runtime library during analysis. */
     auto* cookie() { return &_cookie; }
 
diff --git a/src/spicy/packet-analyzer.h b/src/spicy/packet-analyzer.h
index 8da37afbba..351daa4711 100644
--- a/src/spicy/packet-analyzer.h
+++ b/src/spicy/packet-analyzer.h
@@ -26,6 +26,8 @@ public:
      */
     PacketState(Cookie cookie) : ParsingState(::spicy::rt::driver::ParsingType::Block), _cookie(std::move(cookie)) {}
 
+    virtual ~PacketState() = default;
+
     /** Returns the cookie pointer to use with the runtime library during analysis. */
     auto* cookie() { return &_cookie; }
 
diff --git a/src/spicy/protocol-analyzer.h b/src/spicy/protocol-analyzer.h
index 8ea8bbbe82..affb091235 100644
--- a/src/spicy/protocol-analyzer.h
+++ b/src/spicy/protocol-analyzer.h
@@ -17,6 +17,11 @@
 namespace zeek::spicy::rt {
 
 /** Parsing state for one endpoint of the connection. */
+// FIXME: It's strange that the parent class of this does not have a virtual destructor,
+// but fixing it requires also implementing copy constructor/operators, and it turns into
+// a rabbit hole.
+//
+// NOLINTNEXTLINE(cppcoreguidelines-virtual-class-destructor)
 class EndpointState : public ::spicy::rt::driver::ParsingState {
 public:
     /**
diff --git a/src/threading/BasicThread.h b/src/threading/BasicThread.h
index 8b11e1c2c0..a3e6363c0c 100644
--- a/src/threading/BasicThread.h
+++ b/src/threading/BasicThread.h
@@ -37,6 +37,13 @@ public:
     BasicThread(BasicThread const&) = delete;
     BasicThread& operator=(BasicThread const&) = delete;
 
+    /**
+     * Destructor. This will be called by the manager.
+     *
+     * Only Zeek's main thread may delete thread instances.
+     */
+    virtual ~BasicThread();
+
     /**
      * Returns a descriptive name for the thread. If not set via
      * SetName(), a default name is chosen automatically.
@@ -168,14 +175,6 @@ protected:
      */
     virtual void OnKill() {}
 
-    /**
-     * Destructor. This will be called by the manager.
-     *
-     * Only Zeek's main thread may delete thread instances.
-     *
-     */
-    virtual ~BasicThread();
-
     /**
      * Waits until the thread's Run() method has finished and then joins
      * it. This is called from the threading::Manager.