diff --git a/res/config.ini b/res/config.ini
index be89557..e4eb4ea 100644
--- a/res/config.ini
+++ b/res/config.ini
@@ -12,6 +12,9 @@
 # enable/disable big clock
 #bigclock = true
 
+# Big clock formatting (see strftime specification) [allowed symbols 1-9,-,:]
+#bigclock_format = %c
+
 # The character used to mask the password
 #asterisk = *
 
diff --git a/src/draw.c b/src/draw.c
index 4855a77..ba0692f 100644
--- a/src/draw.c
+++ b/src/draw.c
@@ -240,11 +240,11 @@ void alpha_blit(struct tb_cell* buf, uint16_t x, uint16_t y, uint16_t w, uint16_
 
 void draw_bigclock(struct term_buf* buf)
 {
-	if (!config.bigclock)
+  uint32_t bigclocklength = strlen(config.bigclock_format);
+	if (!config.bigclock || bigclocklength == 0)
     {
         return;
     }
-  uint32_t bigclocklength = strlen(config.bigclock_format);
 	
   int xo = (buf->width / 2) - bigclocklength * (CLOCK_W+1) / 2;
 	int yo = (buf->height - buf->box_height) / 2 - CLOCK_H - 2;