diff --git a/tools/qfbsp/include/options.h b/tools/qfbsp/include/options.h
index 50654fff5..5a674f39c 100644
--- a/tools/qfbsp/include/options.h
+++ b/tools/qfbsp/include/options.h
@@ -39,6 +39,7 @@ typedef struct {
 	qboolean	noclip;
 	qboolean	onlyents;
 	qboolean	usehulls;
+	qboolean	watervis;
 	int			hullnum;
 	int			subdivide_size;
 	char		*mapfile;
diff --git a/tools/qfbsp/source/options.c b/tools/qfbsp/source/options.c
index 7b290ff28..a52ae1252 100644
--- a/tools/qfbsp/source/options.c
+++ b/tools/qfbsp/source/options.c
@@ -61,6 +61,7 @@ static struct option const long_options[] = {
 	{"hullnum",		required_argument,	0, 'H'},
 	{"subdivide",	required_argument,	0, 's'},	
 	{"wadpath",		required_argument,	0, 'w'},
+	{"watervis",	no_argument,		0, 'W'},
 	{NULL, 0, NULL, 0}
 };
 
@@ -78,6 +79,7 @@ static const char *short_options =
 	"H:"	// hullnum
 	"s:"	// subdivide
 	"w:"	// wadpath
+	"W"		// watervis
 	;
 
 
@@ -99,8 +101,10 @@ usage (int status)
 		"    -u, --usehulls            Use the existing hull files\n"
 		"    -H, --hullnum [num]\n"
 		"    -s, --subdivide [size]\n"
-		"    -w, --wadpath [path]      semicolon sparated set of dirs to \n"
-		"                              search for texture wads\n");
+		"    -w, --wadpath [path]      semicolon sparated set of dirs to\n"
+		"                              search for texture wads\n"
+		"    -W, --watervis            allow transparent liquid surfaces\n"
+	);
 	exit (status);
 }
 
@@ -156,6 +160,9 @@ DecodeArgs (int argc, char **argv)
 			case 'w':					// wadpath
 				options.wadpath = optarg;
 				break;
+			case 'W':					// watervis
+				options.watervis = true;
+				break;
 			default:
 				usage (1);
 		}
diff --git a/tools/qfbsp/source/portals.c b/tools/qfbsp/source/portals.c
index 5548e2f64..1938481da 100644
--- a/tools/qfbsp/source/portals.c
+++ b/tools/qfbsp/source/portals.c
@@ -330,7 +330,6 @@ int         num_visleafs;				// leafs the player can be in
 int         num_visportals;
 int         num_realleafs;
 
-//FIXME make work with transparent water
 static int
 HasContents (node_t *n, int cont)
 {
@@ -363,6 +362,10 @@ SameContents (node_t *n1, node_t *n2)
 {
 	if (n1->contents == CONTENTS_SOLID || n2->contents == CONTENTS_SOLID)
 		return 0;
+	if (n1->contents == CONTENTS_SKY || n2->contents == CONTENTS_SKY)
+		return 0;
+	if (options.watervis)	//FIXME be more picky?
+		return 1;
 	if (n1->detail && n2->detail)
 		ShareContents (n1, n2);
 	if (n1->detail)