diff --git a/src/asm/main.c b/src/asm/main.c
index a833295d..d2d30116 100644
--- a/src/asm/main.c
+++ b/src/asm/main.c
@@ -270,7 +270,7 @@ PrintUsage(void)
 	    "\t\t\t(default is 01)\n");
 	printf
 	    ("\t-z<hx>\t\tSet the byte value (hex format) used for uninitialised\n"
-	    "\t\t\tdata (default is ? for random)\n");
+	    "\t\t\tdata (? for random, default is 0x00)\n");
 	exit(0);
 }
 /*
diff --git a/src/link/main.c b/src/link/main.c
index 0a144f89..0ca72430 100644
--- a/src/link/main.c
+++ b/src/link/main.c
@@ -56,7 +56,7 @@ PrintUsage(void)
 	    "\t-m<mapfile>\tWrite a mapfile\n"
 	    "\t-n<symfile>\tWrite a NO$GMB compatible symfile\n"
 	    "\t-z<hx>\t\tSet the byte value (hex format) used for uninitialised\n"
-	    "\t\t\tdata (default is ? for random)\n"
+	    "\t\t\tdata (? for random, default is 0x00)\n"
 	    "\t-s<symbol>\tPerform smart linking starting with <symbol>\n"
 	    "\t-t\t\tOutput target\n" "\t\t-tg\tGameboy ROM image(default)\n"
 	    "\t\t-ts\tGameboy small mode (32kB)\n"