diff --git a/libraries/ESP8266WiFi/src/include/ClientContext.h b/libraries/ESP8266WiFi/src/include/ClientContext.h
index d53b45394..92e79ee33 100644
--- a/libraries/ESP8266WiFi/src/include/ClientContext.h
+++ b/libraries/ESP8266WiFi/src/include/ClientContext.h
@@ -545,6 +545,7 @@ protected:
     err_t _connected(struct tcp_pcb *pcb, err_t err)
     {
         (void) err;
+        (void) pcb;
         assert(pcb == _pcb);
         assert(_connect_pending);
         esp_schedule();
diff --git a/libraries/ESP8266WiFi/src/include/DataSource.h b/libraries/ESP8266WiFi/src/include/DataSource.h
index 77eb78b67..7f399a058 100644
--- a/libraries/ESP8266WiFi/src/include/DataSource.h
+++ b/libraries/ESP8266WiFi/src/include/DataSource.h
@@ -31,12 +31,14 @@ public:
 
     const uint8_t* get_buffer(size_t size) override
     {
+        (void) size;
         assert(_pos + size <= _size);
         return _data + _pos;
     }
 
     void release_buffer(const uint8_t* buffer, size_t size) override
     {
+        (void) buffer;
         assert(buffer == _data + _pos);
         _pos += size;
     }
@@ -70,6 +72,7 @@ public:
         }
         size_t cb = _stream.readBytes(reinterpret_cast<char*>(_buffer.get()), size);
         assert(cb == size);
+        (void) cb;
         return _buffer.get();
     }