diff --git a/src/screen.c b/src/screen.c
index 715894e2..c7295f33 100644
--- a/src/screen.c
+++ b/src/screen.c
@@ -109,6 +109,10 @@ static void make_keys(void)
  */
 static int alreadyRunningError(Display * dpy, XErrorEvent * error)
 {
+	/* Parameter not used, but tell the compiler that it is ok */
+	(void) dpy;
+	(void) error;
+
 	CantManageScreen = 1;
 	return -1;
 }
@@ -520,7 +524,7 @@ WScreen *wScreenInit(int screen_number)
 	scr->fakeGroupLeaders = WMCreateArray(16);
 
 	CantManageScreen = 0;
-	oldHandler = XSetErrorHandler((XErrorHandler) alreadyRunningError);
+	oldHandler = XSetErrorHandler(alreadyRunningError);
 
 	event_mask = EVENT_MASK;
 
diff --git a/src/startup.c b/src/startup.c
index ce5a7741..78422e1a 100644
--- a/src/startup.c
+++ b/src/startup.c
@@ -127,6 +127,9 @@ static int catchXError(Display * dpy, XErrorEvent * error)
  */
 static int handleXIO(Display * xio_dpy)
 {
+	/* Parameter not used, but tell the compiler that it is ok */
+	(void) xio_dpy;
+
 	dpy = NULL;
 	Exit(0);
 	return 0;
diff --git a/src/texture.c b/src/texture.c
index a401fcee..c73c85a0 100644
--- a/src/texture.c
+++ b/src/texture.c
@@ -110,6 +110,10 @@ WTexSolid *wTextureMakeSolid(WScreen * scr, XColor * color)
 
 static int dummyErrorHandler(Display * foo, XErrorEvent * bar)
 {
+	/* Parameter not used, but tell the compiler that it is ok */
+	(void) foo;
+	(void) bar;
+
 	return 0;
 }