diff --git a/bar.c b/bar.c
index 56d5e97b..f54bdced 100644
--- a/bar.c
+++ b/bar.c
@@ -76,6 +76,8 @@ static int i3bar_dump_key(const char *key, const char *value, void *data)
 	bool escape;
 	int err;
 
+	(void)data;
+
 	/* Skip unknown keys */
 	if (!index)
 		return 0;
@@ -154,12 +156,16 @@ static void term_reset_cursor(void)
 
 static void term_start(struct bar *bar)
 {
+	(void) bar;
+
 	term_save_cursor();
 	term_restore_cursor();
 }
 
 static void term_stop(struct bar *bar)
 {
+	(void) bar;
+
 	term_reset_cursor();
 }
 
@@ -260,6 +266,8 @@ static void i3bar_start(struct bar *bar)
 
 static void i3bar_stop(struct bar *bar)
 {
+	(void)bar;
+
 	/* From now on the bar can handle log messages */
 	log_handle = NULL;
 	log_data = NULL;
diff --git a/block.c b/block.c
index c4a8cad6..fd58bfb6 100644
--- a/block.c
+++ b/block.c
@@ -59,6 +59,8 @@ static int block_setenv(const char *name, const char *value, void *data)
 {
 	int err;
 
+	(void)data;
+
 	if (!value)
 		value = "";
 
@@ -233,6 +235,8 @@ void block_touch(struct block *block)
 	unsigned long now;
 	int err;
 
+	(void)block;
+
 	err = sys_gettime(&now);
 	if (err) {
 		block_error(block, "failed to touch block");
@@ -252,6 +256,8 @@ static int block_child_sig(struct block *block)
 	sigset_t set;
 	int err;
 
+	(void)block;
+
 	/* It'd be safe to assume that all signals are unblocked by default */
 	err = sys_sigfillset(&set);
 	if (err)
diff --git a/ini.c b/ini.c
index 4a494ff4..7e984541 100644
--- a/ini.c
+++ b/ini.c
@@ -47,6 +47,8 @@ static int ini_property(struct ini *ini, char *key, char *value)
 
 static int ini_parse_line(char *line, size_t num, void *data)
 {
+	(void)num;
+
 	/* comment or empty line? */
 	if (*line == '\0' || *line == '#')
 		return 0;
diff --git a/json.c b/json.c
index 723b91f6..65b4ca88 100644
--- a/json.c
+++ b/json.c
@@ -347,6 +347,8 @@ static int json_line_cb(char *line, size_t num, void *data)
 	size_t len;
 	int err;
 
+	(void)num;
+
 	for (;;) {
 		/* Only support inline flattened structures at the moment */
 		while (*line == '[' || *line == ']' || *line == ',' ||