diff --git a/Makefile b/Makefile
index 3225e36..b2d5c94 100644
--- a/Makefile
+++ b/Makefile
@@ -8,7 +8,7 @@ all: herbe
 config.h: config.def.h
 	cp config.def.h config.h
 
-herbe: herbe.c config.h
+herbe: herbe.c config.h Makefile
 	$(CC) herbe.c $(CFLAGS) -o herbe
 
 install: herbe
diff --git a/herbe.c b/herbe.c
index 51d3990..a9b8e2a 100644
--- a/herbe.c
+++ b/herbe.c
@@ -15,9 +15,9 @@
 #define EXIT_FAIL 1
 #define EXIT_DISMISS 2
 
-Display *display;
-Window window;
-int exit_code = EXIT_DISMISS;
+static Display *display;
+static Window window;
+static int exit_code = EXIT_DISMISS;
 
 static void die(const char *format, ...)
 {
@@ -29,7 +29,7 @@ static void die(const char *format, ...)
 	exit(EXIT_FAIL);
 }
 
-int get_max_len(char *string, XftFont *font, int max_text_width)
+static int get_max_len(char *string, XftFont *font, int max_text_width)
 {
 	int eol = strlen(string);
 	XGlyphInfo info;
@@ -70,7 +70,7 @@ int get_max_len(char *string, XftFont *font, int max_text_width)
 		return ++eol;
 }
 
-void expire(int sig)
+static void expire(int sig)
 {
 	XEvent event;
 	event.type = ButtonPress;
@@ -117,9 +117,11 @@ int main(int argc, char *argv[])
 	XSetWindowAttributes attributes;
 	attributes.override_redirect = True;
 	XftColor color;
-	XftColorAllocName(display, visual, colormap, background_color, &color);
+	if (!XftColorAllocName(display, visual, colormap, background_color, &color))
+		die("Failed to allocate background color");
 	attributes.background_pixel = color.pixel;
-	XftColorAllocName(display, visual, colormap, border_color, &color);
+	if (!XftColorAllocName(display, visual, colormap, border_color, &color))
+		die("Failed to allocate border color");
 	attributes.border_pixel = color.pixel;
 
 	int num_of_lines = 0;
@@ -130,6 +132,8 @@ int main(int argc, char *argv[])
 		die("malloc failed");
 
 	XftFont *font = XftFontOpenName(display, screen, font_pattern);
+	if (!font)
+		die("Couldn't open font");
 
 	for (int i = 1; i < argc; i++)
 	{
@@ -166,12 +170,16 @@ int main(int argc, char *argv[])
 						   CopyFromParent, visual, CWOverrideRedirect | CWBackPixel | CWBorderPixel, &attributes);
 
 	XftDraw *draw = XftDrawCreate(display, window, visual, colormap);
+	if (!draw)
+		die("Failed to create Xft drawable object");
 	XftColorAllocName(display, visual, colormap, font_color, &color);
 
 	XSelectInput(display, window, ExposureMask | ButtonPress);
 	XMapWindow(display, window);
 
 	sem_t *mutex = sem_open("/herbe", O_CREAT, 0644, 1);
+	if (mutex == SEM_FAILED)
+		die("Failed to open semaphore");
 	sem_wait(mutex);
 
 	sigaction(SIGUSR1, &act_expire, 0);
@@ -217,4 +225,4 @@ int main(int argc, char *argv[])
 	XCloseDisplay(display);
 
 	return exit_code;
-}
\ No newline at end of file
+}