diff --git a/qbsp/qbsp.h b/qbsp/qbsp.h
index 32b183f2..decc5a6c 100644
--- a/qbsp/qbsp.h
+++ b/qbsp/qbsp.h
@@ -396,6 +396,7 @@ typedef struct surface_s {
     vec3_t mins, maxs;
     bool onnode;		// true if surface has already been used
 				//   as a splitting node
+    bool detail_separator;	// true if generated by a detail brush
     face_t *faces;		// links to all faces on either side of the surf
 } surface_t;
 
@@ -420,6 +421,7 @@ typedef struct node_s {
     int visleafnum;		// -1 = solid
     int valid;			// for flood filling
     int occupied;		// entity number in leaf for outside filling
+    bool detail_separator;	// for vis portal generation
 } node_t;
 
 //=============================================================================
diff --git a/qbsp/solidbsp.c b/qbsp/solidbsp.c
index aa7cf83a..1f6972f2 100644
--- a/qbsp/solidbsp.c
+++ b/qbsp/solidbsp.c
@@ -358,8 +358,10 @@ ChoosePlaneFromList(surface_t *surfaces, vec3_t mins, vec3_t maxs)
 	}
 
 	/* If we found a candidate on first pass, don't do a second pass */
-	if (bestsurface)
+	if (pass > 0 && bestsurface) {
+	    bestsurface->detail_separator = true;
 	    break;
+	}
     }
 
     return bestsurface;
@@ -704,6 +706,7 @@ PartitionSurfaces(surface_t *surfaces, node_t *node)
     node->children[0] = AllocMem(NODE, 1, true);
     node->children[1] = AllocMem(NODE, 1, true);
     node->planenum = split->planenum;
+    node->detail_separator = split->detail_separator;
 
     splitplane = &map.planes[split->planenum];