diff --git a/esphome/components/canbus/canbus.h b/esphome/components/canbus/canbus.h
index 56e2f2719b..51d7c0830a 100644
--- a/esphome/components/canbus/canbus.h
+++ b/esphome/components/canbus/canbus.h
@@ -105,9 +105,9 @@ class Canbus : public Component {
   CallbackManager<void(uint32_t can_id, bool extended_id, bool rtr, const std::vector<uint8_t> &data)>
       callback_manager_{};
 
-  virtual bool setup_internal();
-  virtual Error send_message(struct CanFrame *frame);
-  virtual Error read_message(struct CanFrame *frame);
+  virtual bool setup_internal() = 0;
+  virtual Error send_message(struct CanFrame *frame) = 0;
+  virtual Error read_message(struct CanFrame *frame) = 0;
 };
 
 template<typename... Ts> class CanbusSendAction : public Action<Ts...>, public Parented<Canbus> {
diff --git a/esphome/components/mcp23xxx_base/mcp23xxx_base.h b/esphome/components/mcp23xxx_base/mcp23xxx_base.h
index ab7f8ec398..cf0ef5d41c 100644
--- a/esphome/components/mcp23xxx_base/mcp23xxx_base.h
+++ b/esphome/components/mcp23xxx_base/mcp23xxx_base.h
@@ -21,11 +21,11 @@ template<uint8_t N> class MCP23XXXBase : public Component, public gpio_expander:
 
  protected:
   // read a given register
-  virtual bool read_reg(uint8_t reg, uint8_t *value);
+  virtual bool read_reg(uint8_t reg, uint8_t *value) = 0;
   // write a value to a given register
-  virtual bool write_reg(uint8_t reg, uint8_t value);
+  virtual bool write_reg(uint8_t reg, uint8_t value) = 0;
   // update registers with given pin value.
-  virtual void update_reg(uint8_t pin, bool pin_value, uint8_t reg_a);
+  virtual void update_reg(uint8_t pin, bool pin_value, uint8_t reg_a) = 0;
 
   bool open_drain_ints_;
 };