diff --git a/src/Func.cc b/src/Func.cc
index fa08d81709..a5bee5f6e7 100644
--- a/src/Func.cc
+++ b/src/Func.cc
@@ -608,6 +608,9 @@ FuncPtr ScriptFunc::DoClone()
 	{
 	// ScriptFunc could hold a closure. In this case a clone of it must
 	// store a copy of this closure.
+	//
+	// We don't use make_intrusive<> directly because we're accessing
+	// a protected constructor.
 	auto other = IntrusivePtr{AdoptRef{}, new ScriptFunc()};
 
 	CopyStateInto(other.get());
diff --git a/src/Func.h b/src/Func.h
index 14aad967aa..185db5977f 100644
--- a/src/Func.h
+++ b/src/Func.h
@@ -273,6 +273,7 @@ protected:
 	/**
 	 * Uses the given frame for captures, and generates the
 	 * mapping from captured variables to offsets in the frame.
+	 * Virtual so it can be modified for script optimization uses.
 	 *
 	 * @param f  the frame holding the values of capture variables
 	 */
diff --git a/src/Trigger.h b/src/Trigger.h
index 71362ed511..2de6a4686b 100644
--- a/src/Trigger.h
+++ b/src/Trigger.h
@@ -81,6 +81,8 @@ public:
 	// if the Val is null or it's disabled.  The cache is managed using
 	// void*'s so that the value can be associated with either a CallExpr
 	// (for interpreted execution) or a C++ function (for compiled-to-C++).
+	//
+	// Lookup() returned value must be Ref()'d if you want to hang onto it.
 	bool Cache(const void* obj, Val* val);
 	Val* Lookup(const void* obj);
 
diff --git a/src/Var.h b/src/Var.h
index 51a6543202..29cd2ce604 100644
--- a/src/Var.h
+++ b/src/Var.h
@@ -38,7 +38,7 @@ extern void add_global(const IDPtr& id, TypePtr t, InitClass c, ExprPtr init,
 extern StmtPtr add_local(IDPtr id, TypePtr t, InitClass c, ExprPtr init,
                          std::unique_ptr<std::vector<AttrPtr>> attr, DeclType dt);
 
-extern ExprPtr add_and_assign_local(IDPtr id, ExprPtr init, ValPtr val = nullptr);
+extern ExprPtr add_and_assign_local(IDPtr id, ExprPtr init, ValPtr val);
 
 extern void add_type(ID* id, TypePtr t, std::unique_ptr<std::vector<AttrPtr>> attr);
 
diff --git a/src/script_opt/ZAM/Ops.in b/src/script_opt/ZAM/Ops.in
index 89bfccdc35..7350622cbb 100644
--- a/src/script_opt/ZAM/Ops.in
+++ b/src/script_opt/ZAM/Ops.in
@@ -12,7 +12,7 @@
 # The Gen-ZAM utility processes this file to generate numerous C++ inclusion
 # files that are then compiled into Zeek.  These files span the range of (1)
 # hooks that enable run-time generation of ZAM code to execute ASTs (which
-# have first been transformed to "reduced" form, (2) specifications of the
+# have first been transformed to "reduced" form), (2) specifications of the
 # properties of the different instructions, (3) code to evaluate (execute)
 # each instruction, and (4) macros (C++ #define's) to aid in writing that
 # code.  See Gen-ZAM.h for a list of the different inclusion files.