diff --git a/i3-config-wizard/main.c b/i3-config-wizard/main.c
index 7f9f2d64..f3c33034 100644
--- a/i3-config-wizard/main.c
+++ b/i3-config-wizard/main.c
@@ -631,8 +631,6 @@ static void handle_button_press(xcb_button_press_event_t *event) {
         modifier = MOD_Mod1;
         handle_expose();
     }
-
-    return;
 }
 
 /*
diff --git a/i3-nagbar/main.c b/i3-nagbar/main.c
index e4628e30..3e5f43e3 100644
--- a/i3-nagbar/main.c
+++ b/i3-nagbar/main.c
@@ -115,7 +115,7 @@ static void start_application(const char *command) {
         setsid();
         if (fork() == 0) {
             /* This is the child */
-            execl(_PATH_BSHELL, _PATH_BSHELL, "-c", command, (void *)NULL);
+            execl(_PATH_BSHELL, _PATH_BSHELL, "-c", command, NULL);
             /* not reached */
         }
         exit(0);
diff --git a/i3bar/src/xcb.c b/i3bar/src/xcb.c
index 7bfeb12e..800c05d4 100644
--- a/i3bar/src/xcb.c
+++ b/i3bar/src/xcb.c
@@ -2067,5 +2067,4 @@ void set_current_mode(struct mode *current) {
     I3STRING_FREE(binding.name);
     binding = *current;
     activated_mode = binding.name != NULL;
-    return;
 }
diff --git a/libi3/ucs2_conversion.c b/libi3/ucs2_conversion.c
index 75cff78a..398c1ae5 100644
--- a/libi3/ucs2_conversion.c
+++ b/libi3/ucs2_conversion.c
@@ -83,8 +83,7 @@ xcb_char2b_t *convert_utf8_to_ucs2(char *input, size_t *real_strlen) {
     }
 
     /* Do the conversion */
-    size_t rc = iconv(ucs2_conversion_descriptor, (char **)&input,
-                      &input_size, (char **)&output, &output_size);
+    size_t rc = iconv(ucs2_conversion_descriptor, &input, &input_size, (char **)&output, &output_size);
     if (rc == (size_t)-1) {
         perror("Converting to UCS-2 failed");
         free(buffer);
diff --git a/src/handlers.c b/src/handlers.c
index 15c05a8f..38c2caf1 100644
--- a/src/handlers.c
+++ b/src/handlers.c
@@ -184,8 +184,6 @@ static void handle_enter_notify(xcb_enter_notify_event_t *event) {
     focused_id = XCB_NONE;
     con_focus(con_descend_focused(con));
     tree_render();
-
-    return;
 }
 
 /*
@@ -249,8 +247,6 @@ static void handle_mapping_notify(xcb_mapping_notify_event_t *event) {
     ungrab_all_keys(conn);
     translate_keysyms();
     grab_all_keys(conn);
-
-    return;
 }
 
 /*
@@ -266,7 +262,6 @@ static void handle_map_request(xcb_map_request_event_t *event) {
     add_ignore_event(event->sequence, -1);
 
     manage_window(event->window, cookie, false);
-    return;
 }
 
 /*
@@ -474,8 +469,6 @@ static void handle_screen_change(xcb_generic_event_t *e) {
     scratchpad_fix_resolution();
 
     ipc_send_event("output", I3_IPC_EVENT_OUTPUT, "{\"change\":\"unspecified\"}");
-
-    return;
 }
 
 /*
@@ -659,7 +652,6 @@ static void handle_expose_event(xcb_expose_event_t *event) {
     draw_util_copy_surface(&(parent->frame_buffer), &(parent->frame),
                            0, 0, 0, 0, parent->rect.width, parent->rect.height);
     xcb_flush(conn);
-    return;
 }
 
 #define _NET_WM_MOVERESIZE_SIZE_TOPLEFT 0
@@ -1243,7 +1235,6 @@ static void handle_focus_in(xcb_focus_in_event_t *event) {
     /* We update focused_id because we don’t need to set focus again */
     focused_id = event->event;
     tree_render();
-    return;
 }
 
 /*
diff --git a/src/main.c b/src/main.c
index d5d4dcef..de54dbce 100644
--- a/src/main.c
+++ b/src/main.c
@@ -39,8 +39,6 @@ int listen_fds;
  * temporarily for drag_pointer(). */
 static struct ev_prepare *xcb_prepare;
 
-extern Con *focused;
-
 char **start_argv;
 
 xcb_connection_t *conn;
diff --git a/src/manage.c b/src/manage.c
index 9dcc93f5..d591df15 100644
--- a/src/manage.c
+++ b/src/manage.c
@@ -664,5 +664,4 @@ geom_out:
     free(geom);
 out:
     free(attr);
-    return;
 }
diff --git a/src/startup.c b/src/startup.c
index 1e733fcb..b1a2f602 100644
--- a/src/startup.c
+++ b/src/startup.c
@@ -191,7 +191,7 @@ void start_application(const char *command, bool no_startup_id) {
             if (!no_startup_id)
                 sn_launcher_context_setup_child_process(context);
 
-            execl(_PATH_BSHELL, _PATH_BSHELL, "-c", command, (void *)NULL);
+            execl(_PATH_BSHELL, _PATH_BSHELL, "-c", command, NULL);
             /* not reached */
         }
         _exit(0);