diff --git a/.vscode/tasks.json b/.vscode/tasks.json
index 0f8ec0a..c84836f 100644
--- a/.vscode/tasks.json
+++ b/.vscode/tasks.json
@@ -20,6 +20,23 @@
                 "isDefault": true
             }
         },
+        {
+            "label": "check",
+            "type":"shell",
+            "command": "make check -j4",
+            "problemMatcher": {
+                "base": "$gcc",
+                "owner": "gcc",
+                "fileLocation": [
+                    "relative",
+                    "${workspaceFolder}"
+                ]
+            },
+            "group": {
+                "kind": "build",
+                "isDefault": true
+            }
+        },
         {
             "label": "clean",
             "type":"shell",
diff --git a/Makefile b/Makefile
index 6977947..c687448 100644
--- a/Makefile
+++ b/Makefile
@@ -4,6 +4,7 @@ TARGET_FILE ?= test
 
 CC = $(CROSS_COMPILE)gcc
 CPP = $(CROSS_COMPILE)cpp
+CHECK = cppcheck
 
 SRC_DIR = src
 OBJ_DIR = obj
@@ -22,6 +23,7 @@ endif
 LD_FLAGS :=
 C_FLAGS := -O0 -g -Wall -Wextra -Werror
 CPP_FLAGS := $(addprefix -I, $(INCLUDES))
+CHECK_CLAGS := --enable=all --template=gcc --error-exitcode=1 --suppress=missingIncludeSystem
 
 C_SRCS = $(wildcard $(SRC_DIR)/*.c)
 C_OBJS = $(patsubst $(SRC_DIR)%,$(OBJ_DIR)%,$(patsubst %.c,%.o,$(C_SRCS)))
@@ -34,6 +36,10 @@ THIS_MAKEFILE := $(lastword $(MAKEFILE_LIST))
 .PHONY: all
 all: $(TARGET)
 
+.PHONY: check
+check: $(C_SRCS)
+	$(CHECK) $(CPP_FLAGS) $(CHECK_CLAGS) $(C_SRCS)
+
 $(TARGET): $(OBJS) $(THIS_MAKEFILE)
 	@mkdir -p $(BIN_DIR)
 	$(CC) $(C_FLAGS) $(LD_FLAGS) $(OBJS) $(addprefix -l,$(LIBS)) -o $@
diff --git a/src/gpio.c b/src/gpio.c
index c39f8d0..e87b8d8 100644
--- a/src/gpio.c
+++ b/src/gpio.c
@@ -108,12 +108,14 @@ int gpio_read(const struct gpio *gpio, unsigned int *value)
 int gpio_write(const struct gpio *gpio, unsigned int value)
 {
     int res;
-    unsigned char mask = gpio->ftdi_dev->status_mask;
+    unsigned char mask;
 
     if(NULL == gpio) {
         return EXIT_FAILURE;
     }
 
+    mask = gpio->ftdi_dev->status_mask;
+
     if(value == 0) {
         mask &= ~(unsigned char)(gpio->pin);
     }
@@ -135,13 +137,13 @@ int gpio_write(const struct gpio *gpio, unsigned int value)
 int gpio_toggle(const struct gpio *gpio)
 {
     int res;
-    unsigned char mask = gpio->ftdi_dev->status_mask;
+    unsigned char mask;
 
     if(NULL == gpio) {
         return EXIT_FAILURE;
     }
 
-    mask ^= (unsigned char)(gpio->pin);
+    mask  = (gpio->ftdi_dev->status_mask) ^ (unsigned char)(gpio->pin);
 
     res = ftdi_write_data(gpio->ftdi_dev->ftdi, &mask, 1);
     if(res < 0) {