diff --git a/src/Func.cc b/src/Func.cc
index 7464f76ece..64e3ed2a88 100644
--- a/src/Func.cc
+++ b/src/Func.cc
@@ -332,8 +332,11 @@ ScriptFunc::ScriptFunc(std::string _name, FuncTypePtr ft,
 
 	sort(bodies.begin(), bodies.end());
 
-	current_body = bodies[0].stmts;
-	current_priority = bodies[0].priority;
+	if ( bodies.size() > 0 )
+		{
+		current_body = bodies[0].stmts;
+		current_priority = bodies[0].priority;
+		}
 	}
 
 ScriptFunc::~ScriptFunc()
@@ -579,15 +582,22 @@ void ScriptFunc::ReplaceBody(const StmtPtr& old_body, StmtPtr new_body)
 	{
 	bool found_it = false;
 
-	for ( auto& body : bodies )
-		if ( body.stmts.get() == old_body.get() )
+	for ( auto body = bodies.begin(); body != bodies.end(); ++body )
+		if ( body->stmts.get() == old_body.get() )
 			{
-			body.stmts = new_body;
-			current_priority = body.priority;
+			if ( new_body )
+				{
+				body->stmts = new_body;
+				current_priority = body->priority;
+				}
+			else
+				bodies.erase(body);
+
 			found_it = true;
+			break;
 			}
 
-	ASSERT(found_it);
+	// ASSERT(found_it);
 	current_body = new_body;
 	}
 
diff --git a/src/Func.h b/src/Func.h
index c1871270cb..db82bc8447 100644
--- a/src/Func.h
+++ b/src/Func.h
@@ -237,10 +237,16 @@ public:
 	             const std::vector<IDPtr>& new_inits,
 	             size_t new_frame_size, int priority) override;
 
-	// Replace the given current instance of a function body with
-	// a new one.
+	/**
+	 * Replaces the given current instance of a function body with
+	 * a new one.  If new_body is nil then the current instance is
+	 * deleted with no replacement.
+	 *
+	 * @param old_body  Body to replace.
+	 * @param new_body  New body to use; can be nil.
+	 */
 	void ReplaceBody(const detail::StmtPtr& old_body,
-				detail::StmtPtr new_body);
+	                 detail::StmtPtr new_body);
 
 	StmtPtr CurrentBody() const		{ return current_body; }
 	int CurrentPriority() const		{ return current_priority; }
@@ -316,7 +322,7 @@ private:
 	StmtPtr current_body;
 
 	// ... and its priority.
-	int current_priority;
+	int current_priority = 0;
 };
 
 using built_in_func = BifReturnVal (*)(Frame* frame, const Args* args);