diff --git a/includes/powder.h b/includes/powder.h
index a1bb71da7..f198ad735 100644
--- a/includes/powder.h
+++ b/includes/powder.h
@@ -689,7 +689,7 @@ static wall_type wtypes[] =
 	{PIXPACK(0x808080), PIXPACK(0x000000), 0, "Erases walls."},
 	{PIXPACK(0x808080), PIXPACK(0x000000), 3, "Wall. Indestructible. Blocks everything."},
 	{PIXPACK(0x3C3C3C), PIXPACK(0x000000), 1, "Wall. Indestructible. Blocks particles, allows air"},
-	{PIXPACK(0x575757), PIXPACK(0x000000), 1, "Wall. Indestructible. Blocks liquids and gasses, allows solids"},
+	{PIXPACK(0x575757), PIXPACK(0x000000), 1, "Wall. Indestructible. Blocks liquids and gasses, allows powders"},
 	{PIXPACK(0xFFFF22), PIXPACK(0x101010), 2, "Conductor, allows particles, conducts electricity"},
 	{PIXPACK(0x242424), PIXPACK(0x101010), 0, "E-Hole, absorbs particles, release them when powered"},
 	{PIXPACK(0xFFFFFF), PIXPACK(0x000000), -1, "Air, creates airflow and pressure"},
diff --git a/src/main.c b/src/main.c
index 5abc139ab..036bdf16f 100644
--- a/src/main.c
+++ b/src/main.c
@@ -402,6 +402,8 @@ void stamp_save(int x, int y, int w, int h)
 	int n;
 	char fn[64], sn[16];
 	void *s=build_save(&n, x, y, w, h, bmap, vx, vy, pv, fvx, fvy, signs, parts);
+	if (!s)
+		return;
 
 #ifdef WIN32
 	_mkdir("stamps");