diff --git a/config.def.h b/config.def.h
index 054a479..77e2b37 100644
--- a/config.def.h
+++ b/config.def.h
@@ -62,6 +62,7 @@ static const Rule rules[] = {
 	/* class     instance  title           tags mask  isfloating isterminal noswallow   monitor */
 	{ "St",       NULL,      NULL,           0,         0,       1,         0,          -1 },
 	{ NULL,      "float",    NULL,           0,         1,       0,         0,          -1 },
+	{ NULL,      "st-float", NULL,           0,         1,       1,         1,          -1 },
   { NULL,      "spterm0",  NULL,           SPTAG(0),  1,       1,         0,          -1 },
   { NULL,      "spterm1",  NULL,           SPTAG(1),  1,       1,         0,          -1 },
   { NULL,      "spterm2",  NULL,           SPTAG(2),  1,       1,         0,          -1 },