diff --git a/hal/api/AnalogIn.h b/hal/api/AnalogIn.h
index 01b863f555..b30fd610a9 100644
--- a/hal/api/AnalogIn.h
+++ b/hal/api/AnalogIn.h
@@ -103,6 +103,10 @@ public:
     }
 #endif
 
+    virtual ~AnalogIn() {
+        // Do nothing
+    }
+
 protected:
 
     virtual void lock() {
diff --git a/hal/api/AnalogOut.h b/hal/api/AnalogOut.h
index 68488d9709..315ab4e49f 100644
--- a/hal/api/AnalogOut.h
+++ b/hal/api/AnalogOut.h
@@ -122,6 +122,10 @@ public:
     }
 #endif
 
+    virtual ~AnalogOut() {
+        // Do nothing
+    }
+
 protected:
 
     virtual void lock() {
diff --git a/hal/api/I2C.h b/hal/api/I2C.h
index 817c590d6e..38fcdbc3fd 100644
--- a/hal/api/I2C.h
+++ b/hal/api/I2C.h
@@ -145,6 +145,10 @@ public:
      */
     virtual void unlock(void);
 
+    virtual ~I2C() {
+        // Do nothing
+    }
+
 #if DEVICE_I2C_ASYNCH
 
     /** Start non-blocking I2C transfer.
diff --git a/hal/api/InterruptManager.h b/hal/api/InterruptManager.h
index 30c705f1ac..f31fae5dca 100644
--- a/hal/api/InterruptManager.h
+++ b/hal/api/InterruptManager.h
@@ -113,14 +113,13 @@ public:
      */
     bool remove_handler(pFunctionPointer_t handler, IRQn_Type irq);
 
-protected:
-    virtual void lock();
-    virtual void unlock();
-
 private:
     InterruptManager();
     ~InterruptManager();
 
+    void lock();
+    void unlock();
+
     // We declare the copy contructor and the assignment operator, but we don't
     // implement them. This way, if someone tries to copy/assign our instance,
     // he will get an error at compile time.