diff --git a/demos/ARM7-LPC214x-G++/Makefile b/demos/ARM7-LPC214x-G++/Makefile
index 3b0a8bee3..3bb33abfe 100644
--- a/demos/ARM7-LPC214x-G++/Makefile
+++ b/demos/ARM7-LPC214x-G++/Makefile
@@ -126,10 +126,10 @@ AOPT =
 TOPT = -mthumb -DTHUMB
 
 # Define C warning options here
-CWARN = -Wall -Wstrict-prototypes
+CWARN = -Wall -Wextra -Wstrict-prototypes
 
 # Define C++ warning options here
-CPPWARN = -Wall
+CPPWARN = -Wall -Wextra
 
 #
 # Compiler settings
diff --git a/demos/ARM7-LPC214x-G++/main.cpp b/demos/ARM7-LPC214x-G++/main.cpp
index b46ccd86e..f0268045d 100644
--- a/demos/ARM7-LPC214x-G++/main.cpp
+++ b/demos/ARM7-LPC214x-G++/main.cpp
@@ -137,6 +137,7 @@ public:
  */
 static void TimerHandler(eventid_t id) {
 
+  (void)id;
   if (!(palReadPort(IOPORT1) & BOTH_BUTTONS)) { // Both buttons
     TesterThread tester;
     tester.Wait();
@@ -154,6 +155,9 @@ int main(int argc, char **argv) {
   static EvTimer evt;
   struct EventListener el0;
 
+  (void)argc;
+  (void)argv;
+
   /*
    * Activates the serial driver 2 using the driver default configuration.
    */
diff --git a/demos/ARM7-LPC214x-GCC-minimal/Makefile b/demos/ARM7-LPC214x-GCC-minimal/Makefile
index 5315948af..21e9a0eea 100644
--- a/demos/ARM7-LPC214x-GCC-minimal/Makefile
+++ b/demos/ARM7-LPC214x-GCC-minimal/Makefile
@@ -123,10 +123,10 @@ AOPT =
 TOPT = -mthumb -DTHUMB
 
 # Define C warning options here
-CWARN = -Wall -Wstrict-prototypes
+CWARN = -Wall -Wextra -Wstrict-prototypes
 
 # Define C++ warning options here
-CPPWARN = -Wall
+CPPWARN = -Wall -Wextra
 
 #
 # Compiler settings
diff --git a/demos/ARM7-LPC214x-GCC-minimal/main.c b/demos/ARM7-LPC214x-GCC-minimal/main.c
index d303237c4..7ce5ffe95 100644
--- a/demos/ARM7-LPC214x-GCC-minimal/main.c
+++ b/demos/ARM7-LPC214x-GCC-minimal/main.c
@@ -28,6 +28,7 @@
 static WORKING_AREA(waThread1, 128);
 static msg_t Thread1(void *arg) {
 
+  (void)arg;
   while (TRUE) {
     palClearPort(IOPORT1, PAL_PORT_BIT(PA_LED2));
     chThdSleepMilliseconds(200);
@@ -47,6 +48,7 @@ static msg_t Thread1(void *arg) {
 static WORKING_AREA(waThread2, 128);
 static msg_t Thread2(void *arg) {
 
+  (void)arg;
   while (TRUE) {
     palClearPad(IOPORT1, PA_LEDUSB);
     chThdSleepMilliseconds(200);
@@ -62,6 +64,9 @@ static msg_t Thread2(void *arg) {
  */
 int main(int argc, char **argv) {
 
+  (void)argc;
+  (void)argv;
+
   /*
    * Creates the blinker threads.
    */
diff --git a/demos/ARM7-LPC214x-GCC/Makefile b/demos/ARM7-LPC214x-GCC/Makefile
index 54b1e0ffd..792ff4fbd 100644
--- a/demos/ARM7-LPC214x-GCC/Makefile
+++ b/demos/ARM7-LPC214x-GCC/Makefile
@@ -127,10 +127,10 @@ AOPT =
 TOPT = -mthumb -DTHUMB
 
 # Define C warning options here
-CWARN = -Wall -Wstrict-prototypes
+CWARN = -Wall -Wextra -Wstrict-prototypes
 
 # Define C++ warning options here
-CPPWARN = -Wall
+CPPWARN = -Wall -Wextra
 
 #
 # Compiler settings
diff --git a/demos/ARM7-LPC214x-GCC/buzzer.c b/demos/ARM7-LPC214x-GCC/buzzer.c
index 25be0e2d9..1d3350bb2 100644
--- a/demos/ARM7-LPC214x-GCC/buzzer.c
+++ b/demos/ARM7-LPC214x-GCC/buzzer.c
@@ -58,9 +58,8 @@ void InitBuzzer(void) {
 }
 
 static void stop(void *p) {
-  TC *tc = T1Base;
 
-  StopCounter(tc);
+  StopCounter((TC *)p);
   chEvtBroadcastI(&BuzzerSilentEventSource);
 }
 
@@ -77,7 +76,7 @@ void PlaySound(int freq, systime_t duration) {
 
   tc->TC_MR0 = tc->TC_MR1 = (PCLK / (freq * 2));
   StartCounter(tc);
-  chVTSetI(&bvt, duration, stop, NULL);
+  chVTSetI(&bvt, duration, stop, tc);
 
   chSysUnlock();
 }
diff --git a/demos/ARM7-LPC214x-GCC/main.c b/demos/ARM7-LPC214x-GCC/main.c
index a8db1b667..93b6fd768 100644
--- a/demos/ARM7-LPC214x-GCC/main.c
+++ b/demos/ARM7-LPC214x-GCC/main.c
@@ -35,6 +35,7 @@
 static WORKING_AREA(waThread1, 128);
 static msg_t Thread1(void *arg) {
 
+  (void)arg;
   while (TRUE) {
     palClearPort(IOPORT1, PAL_PORT_BIT(PA_LED2));
     chThdSleepMilliseconds(200);
@@ -54,6 +55,7 @@ static msg_t Thread1(void *arg) {
 static WORKING_AREA(waThread2, 128);
 static msg_t Thread2(void *arg) {
 
+  (void)arg;
   while (TRUE) {
     palClearPad(IOPORT1, PA_LEDUSB);
     chThdSleepMilliseconds(200);
@@ -70,6 +72,7 @@ static WORKING_AREA(waTestThread, 128);
  */
 static void TimerHandler(eventid_t id) {
 
+  (void)id;
   if (!(palReadPort(IOPORT1) & BOTH_BUTTONS)) {
     Thread *tp = chThdCreateStatic(waTestThread, sizeof(waTestThread),
                                    NORMALPRIO, TestThread, &SD1);
@@ -94,6 +97,7 @@ static void InsertHandler(eventid_t id) {
   static uint8_t rwbuf[512];
   MMCCSD data;
 
+  (void)id;
   PlaySoundWait(1000, MS2ST(100));
   PlaySoundWait(2000, MS2ST(100));
   if (mmcInit())
@@ -111,6 +115,7 @@ static void InsertHandler(eventid_t id) {
  */
 static void RemoveHandler(eventid_t id) {
 
+  (void)id;
   PlaySoundWait(2000, MS2ST(100));
   PlaySoundWait(1000, MS2ST(100));
 }
@@ -128,6 +133,9 @@ int main(int argc, char **argv) {
   static EvTimer evt;
   struct EventListener el0, el1, el2;
 
+  (void)argc;
+  (void)argv;
+
   /*
    * Activates the serial driver 2 using the driver default configuration.
    */
diff --git a/demos/ARM7-LPC214x-GCC/mmcsd.c b/demos/ARM7-LPC214x-GCC/mmcsd.c
index aba532544..731f594a2 100644
--- a/demos/ARM7-LPC214x-GCC/mmcsd.c
+++ b/demos/ARM7-LPC214x-GCC/mmcsd.c
@@ -42,6 +42,7 @@ void InitMMC(void) {
 
 void tmrfunc(void *par) {
 
+  (void)par;
   if (cnt) {
     if (!palReadPad(IOPORT2, PB_CP1)) {
       if (!--cnt)
diff --git a/demos/ARMCM3-STM32F103-GCC/Makefile b/demos/ARMCM3-STM32F103-GCC/Makefile
index ca12fd05d..4919e567e 100644
--- a/demos/ARMCM3-STM32F103-GCC/Makefile
+++ b/demos/ARMCM3-STM32F103-GCC/Makefile
@@ -139,10 +139,10 @@ AOPT =
 TOPT = -mthumb -DTHUMB
 
 # Define C warning options here
-CWARN = -Wall -Wstrict-prototypes
+CWARN = -Wall -Wextra -Wstrict-prototypes
 
 # Define C++ warning options here
-CPPWARN = -Wall
+CPPWARN = -Wall -Wextra
 
 #
 # Compiler settings
diff --git a/demos/ARMCM3-STM32F103-GCC/main.c b/demos/ARMCM3-STM32F103-GCC/main.c
index ca2fa842b..fcc496648 100644
--- a/demos/ARMCM3-STM32F103-GCC/main.c
+++ b/demos/ARMCM3-STM32F103-GCC/main.c
@@ -30,6 +30,7 @@
 static WORKING_AREA(waThread1, 128);
 static msg_t Thread1(void *arg) {
 
+  (void)arg;
   while (TRUE) {
     palClearPad(IOPORT3, GPIOC_LED);
     chThdSleepMilliseconds(500);
@@ -45,6 +46,9 @@ static msg_t Thread1(void *arg) {
  */
 int main(int argc, char **argv) {
 
+  (void)argc;
+  (void)argv;
+
   /*
    * Activates the serial driver 2 using the driver default configuration.
    */
diff --git a/demos/MSP430-MSP430x1611-GCC/Makefile b/demos/MSP430-MSP430x1611-GCC/Makefile
index dc3747875..7a7a720a8 100644
--- a/demos/MSP430-MSP430x1611-GCC/Makefile
+++ b/demos/MSP430-MSP430x1611-GCC/Makefile
@@ -91,10 +91,10 @@ HEX  = $(CP) -O ihex
 BIN  = $(CP) -O binary
 
 # Define C warning options here
-CWARN = -Wall -Wstrict-prototypes
+CWARN = -Wall -Wextra -Wstrict-prototypes
 
 # Define C++ warning options here
-CPPWARN = -Wall
+CPPWARN = -Wall -Wextra
 
 #
 # Compiler settings
diff --git a/demos/MSP430-MSP430x1611-GCC/main.c b/demos/MSP430-MSP430x1611-GCC/main.c
index 02622e817..3e729296b 100644
--- a/demos/MSP430-MSP430x1611-GCC/main.c
+++ b/demos/MSP430-MSP430x1611-GCC/main.c
@@ -30,6 +30,7 @@
 static WORKING_AREA(waThread1, 64);
 static msg_t Thread1(void *arg) {
 
+  (void)arg;
   while (TRUE) {
     palSetPad(IOPORT6, P6_O_LED);
     chThdSleepMilliseconds(500);
@@ -44,6 +45,9 @@ static msg_t Thread1(void *arg) {
  */
 int main(int argc, char **argv) {
 
+  (void)argc;
+  (void)argv;
+
   /*
    * Hardware initialization, see board.c.
    */
diff --git a/demos/Win32-MinGW/Makefile b/demos/Win32-MinGW/Makefile
index f700ce159..3552537ad 100644
--- a/demos/Win32-MinGW/Makefile
+++ b/demos/Win32-MinGW/Makefile
@@ -99,7 +99,7 @@ LIBS    = $(DLIBS) $(ULIBS)
 
 LDFLAGS = -Wl,-Map=$(PROJECT).map,--cref,--no-warn-mismatch $(LIBDIR)
 ASFLAGS = -Wa,-amhls=$(<:.s=.lst) $(ADEFS)
-CPFLAGS = $(OPT) -Wall -Wstrict-prototypes -fverbose-asm -Wa,-alms=$(<:.c=.lst) $(DEFS)
+CPFLAGS = $(OPT) -Wall -Wextra -Wstrict-prototypes -fverbose-asm -Wa,-alms=$(<:.c=.lst) $(DEFS)
 
 # Generate dependency information
 CPFLAGS += -MD -MP -MF .dep/$(@F).d
diff --git a/demos/Win32-MinGW/chcore.c b/demos/Win32-MinGW/chcore.c
index 95d8b9de8..8dcb3b9ad 100644
--- a/demos/Win32-MinGW/chcore.c
+++ b/demos/Win32-MinGW/chcore.c
@@ -89,8 +89,9 @@ void ChkIntSources(void) {
  */
 __attribute__((used))
 static void __dummy(Thread *otp, Thread *ntp) {
+  (void)otp; (void)ntp;
   asm volatile (".globl @port_switch@8                          \n\t" \
-               "@port_switch@8:                                 \n\t" \
+                "@port_switch@8:                                \n\t" \
                 "push    %ebp                                   \n\t" \
                 "push    %esi                                   \n\t" \
                 "push    %edi                                   \n\t" \
diff --git a/demos/Win32-MinGW/main.c b/demos/Win32-MinGW/main.c
index bca8af11b..6a2b5367f 100644
--- a/demos/Win32-MinGW/main.c
+++ b/demos/Win32-MinGW/main.c
@@ -42,10 +42,11 @@ msg_t TestThread(void *p);
  * areas. The system is halted if something is wrong.
  */
 static msg_t WatchdogThread(void *arg) {
+
+  (void)arg;
   wdguard = 0xA51F2E3D;
   cdguard = 0xA51F2E3D;
   while (TRUE) {
-
     if ((wdguard != 0xA51F2E3D) ||
         (cdguard != 0xA51F2E3D)) {
       printf("Halted by watchdog");
@@ -64,6 +65,7 @@ static msg_t WatchdogThread(void *arg) {
  */
 static msg_t ConsoleThread(void *arg) {
 
+  (void)arg;
   while (!chThdShouldTerminate()) {
     printf((char *)chMsgWait());
     fflush(stdout);
@@ -230,6 +232,7 @@ EventListener s1tel;
 static void COM1Handler(eventid_t id) {
   sdflags_t flags;
 
+  (void)id;
   if (s1 && chThdTerminated(s1)) {
     s1 = NULL;
     cprint("Init: disconnection on SD1\n");
@@ -256,6 +259,7 @@ EventListener s2tel;
 static void COM2Handler(eventid_t id) {
   sdflags_t flags;
 
+  (void)id;
   if (s2 && chThdTerminated(s2)) {
     s2 = NULL;
     cprint("Init: disconnection on SD2\n");
diff --git a/os/io/platforms/Win32/serial_lld.c b/os/io/platforms/Win32/serial_lld.c
index 2539ebae9..ab8384254 100644
--- a/os/io/platforms/Win32/serial_lld.c
+++ b/os/io/platforms/Win32/serial_lld.c
@@ -241,6 +241,7 @@ void sd_lld_start(SerialDriver *sdp, const SerialDriverConfig *config) {
  */
 void sd_lld_stop(SerialDriver *sdp) {
 
+  (void)sdp;
 }
 
 bool_t sd_lld_interrupt_pending(void) {
diff --git a/os/kernel/include/queues.h b/os/kernel/include/queues.h
index 9082ea5f7..25ba82d65 100644
--- a/os/kernel/include/queues.h
+++ b/os/kernel/include/queues.h
@@ -27,6 +27,8 @@
 #ifndef _QUEUES_H_
 #define _QUEUES_H_
 
+#if CH_USE_QUEUES
+
 /*
  * Module dependancies check.
  */
@@ -48,7 +50,6 @@ typedef void (*qnotify_t)(void);
 /** Returned by the queue functions if the queue is full. */
 #define Q_FULL          -4
 
-#if CH_USE_QUEUES
 /**
  * @brief Generic I/O queue structure.
  * @details This structure represents a generic Input or Output asymmetrical
diff --git a/os/ports/GCC/ARMCM3/chcore.c b/os/ports/GCC/ARMCM3/chcore.c
index fbf201a56..8f99d3dec 100644
--- a/os/ports/GCC/ARMCM3/chcore.c
+++ b/os/ports/GCC/ARMCM3/chcore.c
@@ -92,22 +92,22 @@ void SVCallVector(Thread *otp, Thread *ntp) {
   asm volatile ("mrs     r3, BASEPRI                            \n\t" \
                 "mrs     r12, PSP                               \n\t" \
                 "stmdb   r12!, {r3-r6,r8-r11, lr}               \n\t" \
-                "str     r12, [r0, #16]                         \n\t" \
-                "ldr     r12, [r1, #16]                         \n\t" \
+                "str     r12, [%0, #16]                         \n\t" \
+                "ldr     r12, [%1, #16]                         \n\t" \
                 "ldmia   r12!, {r3-r6,r8-r11, lr}               \n\t" \
                 "msr     PSP, r12                               \n\t" \
                 "msr     BASEPRI, r3                            \n\t" \
-                "bx      lr                                     ");
+                "bx      lr" : : "r" (otp), "r" (ntp));
 #else
   asm volatile ("mrs     r3, BASEPRI                            \n\t" \
                 "mrs     r12, PSP                               \n\t" \
                 "stmdb   r12!, {r3-r11, lr}                     \n\t" \
-                "str     r12, [r0, #16]                         \n\t" \
-                "ldr     r12, [r1, #16]                         \n\t" \
+                "str     r12, [%0, #16]                         \n\t" \
+                "ldr     r12, [%1, #16]                         \n\t" \
                 "ldmia   r12!, {r3-r11, lr}                     \n\t" \
                 "msr     PSP, r12                               \n\t" \
                 "msr     BASEPRI, r3                            \n\t" \
-                "bx      lr                                     ");
+                "bx      lr" : : "r" (otp), "r" (ntp));
 #endif
 }
 
diff --git a/readme.txt b/readme.txt
index c2314df04..e5dcb6944 100644
--- a/readme.txt
+++ b/readme.txt
@@ -20,6 +20,8 @@
 - CHANGE: Because the changes in the allocators some configuration options
   changed, see the template chconf.h file.
 - CHANGE: renamed ./demos/ARM7-AT91SAM7X-WEB-GCC in ARM7-AT91SAM7X-UIP-GCC.
+- FIX: Added the most restrictive GCC warning option to the makefiles (-Wextra)
+  and fixed some warnings in the code, mostly unused function parameters.
 
 *** 1.3.2 ***
 - FIX: Fixed GCC 4.4.x aliasing warnings (bug 2846336)(backported in stable
diff --git a/test/coverage/Makefile b/test/coverage/Makefile
index fb069123c..adefad74b 100644
--- a/test/coverage/Makefile
+++ b/test/coverage/Makefile
@@ -96,7 +96,7 @@ LIBS    = $(DLIBS) $(ULIBS)
 
 LDFLAGS = -Wl,-Map=$(PROJECT).map,--cref,--no-warn-mismatch -lgcov $(LIBDIR)
 ASFLAGS = -Wa,-amhls=$(<:.s=.lst) $(ADEFS)
-CPFLAGS = $(OPT) -Wall -Wstrict-prototypes -fverbose-asm -Wa,-alms=$(<:.c=.lst) $(DEFS)
+CPFLAGS = $(OPT) -Wall -Wextra -Wstrict-prototypes -fverbose-asm -Wa,-alms=$(<:.c=.lst) $(DEFS)
 
 # Generate dependency information
 CPFLAGS += -MD -MP -MF .dep/$(@F).d
diff --git a/test/coverage/chcore.c b/test/coverage/chcore.c
index 9ec3dd9f5..6b934ad9a 100644
--- a/test/coverage/chcore.c
+++ b/test/coverage/chcore.c
@@ -84,8 +84,9 @@ void ChkIntSources(void) {
  */
 __attribute__((used))
 static void __dummy(Thread *otp, Thread *ntp) {
+  (void)otp; (void)ntp;
   asm volatile (".globl @port_switch@8                          \n\t" \
-               "@port_switch@8:                                 \n\t" \
+                "@port_switch@8:                                \n\t" \
                 "push    %ebp                                   \n\t" \
                 "push    %esi                                   \n\t" \
                 "push    %edi                                   \n\t" \
diff --git a/test/coverage/main.c b/test/coverage/main.c
index 893747546..923fb12c2 100644
--- a/test/coverage/main.c
+++ b/test/coverage/main.c
@@ -30,6 +30,9 @@
 int main(int argc, char *argv[]) {
   msg_t result;
 
+  (void)argc;
+  (void)argv;
+
   chSysInit();
   sdStart(&SD1, NULL);
 
diff --git a/test/coverage/serial_lld.c b/test/coverage/serial_lld.c
index 70c073648..e1f3897a1 100644
--- a/test/coverage/serial_lld.c
+++ b/test/coverage/serial_lld.c
@@ -92,6 +92,7 @@ void sd_lld_init(void) {
  */
 void sd_lld_start(SerialDriver *sdp, const SerialDriverConfig *config) {
 
+  (void)sdp;
   if (config == NULL)
     config = &default_config;
 
@@ -106,6 +107,7 @@ void sd_lld_start(SerialDriver *sdp, const SerialDriverConfig *config) {
  */
 void sd_lld_stop(SerialDriver *sdp) {
 
+  (void)sdp;
 }
 
 bool_t sd_lld_interrupt_pending(void) {