diff --git a/common/bspfile.cc b/common/bspfile.cc
index f155b9e0..fa0eac55 100644
--- a/common/bspfile.cc
+++ b/common/bspfile.cc
@@ -109,7 +109,7 @@ private:
     // todo: this should be the only state inside a contentflags_t in q1 mode.
     struct q1_contentflags_bits
     {
-        using bitset_t = std::bitset<14>;
+        using bitset_t = std::bitset<15>;
 
         // visible contents
         bool solid = false;
@@ -129,6 +129,7 @@ private:
         // content flags
         bool detail = false;
         bool mirror_inside = false;
+        bool mirror_inside_set = false; // whether to use mirror_inside (if false, use content default)
         bool suppress_clipping_same_type = false;
 
         constexpr size_t last_visible_contents() const { return 7; }
@@ -148,7 +149,8 @@ private:
             result[10] = illusionary_visblocker;
             result[11] = detail;
             result[12] = mirror_inside;
-            result[13] = suppress_clipping_same_type;
+            result[13] = mirror_inside_set;
+            result[14] = suppress_clipping_same_type;
             return result;
         }
 
@@ -167,12 +169,13 @@ private:
               illusionary_visblocker(bitset[10]),
               detail(bitset[11]),
               mirror_inside(bitset[12]),
-              suppress_clipping_same_type(bitset[13])
+              mirror_inside_set(bitset[13]),
+              suppress_clipping_same_type(bitset[14])
         {
         }
 
         static constexpr const char *bitflag_names[] = {"SOLID", "SKY", "WALL", "FENCE", "LAVA", "SLIME", "WATER",
-            "MIST", "ORIGIN", "CLIP", "ILLUSIONARY_VISBLOCKER", "DETAIL", "MIRROR_INSIDE",
+            "MIST", "ORIGIN", "CLIP", "ILLUSIONARY_VISBLOCKER", "DETAIL", "MIRROR_INSIDE", "MIRROR_INSIDE_SET",
             "SUPPRESS_CLIPPING_SAME_TYPE"};
 
         constexpr bool operator[](size_t index) const
@@ -191,7 +194,8 @@ private:
                 case 10: return illusionary_visblocker;
                 case 11: return detail;
                 case 12: return mirror_inside;
-                case 13: return suppress_clipping_same_type;
+                case 13: return mirror_inside_set;
+                case 14: return suppress_clipping_same_type;
                 default: throw std::out_of_range("index");
             }
         }
@@ -212,7 +216,8 @@ private:
                 case 10: return illusionary_visblocker;
                 case 11: return detail;
                 case 12: return mirror_inside;
-                case 13: return suppress_clipping_same_type;
+                case 13: return mirror_inside_set;
+                case 14: return suppress_clipping_same_type;
                 default: throw std::out_of_range("index");
             }
         }
@@ -270,6 +275,7 @@ private:
             // clear flags
             this_test.detail = false;
             this_test.mirror_inside = false;
+            this_test.mirror_inside_set = false;
             this_test.suppress_clipping_same_type = false;
 
             q1_contentflags_bits empty_test;
@@ -300,6 +306,7 @@ private:
         result.detail = data.is_detail;
 
         result.illusionary_visblocker = contents.illusionary_visblocker;
+        result.mirror_inside_set = contents.mirror_inside.has_value();
         result.mirror_inside = contents.mirror_inside.value_or(false);
         result.suppress_clipping_same_type = !contents.clips_same_type.value_or(true);
 
@@ -339,7 +346,11 @@ private:
         }
 
         result.illusionary_visblocker = bits.illusionary_visblocker;
-        result.mirror_inside = bits.mirror_inside;
+        if (bits.mirror_inside_set) {
+            result.mirror_inside = bits.mirror_inside;
+        } else {
+            result.mirror_inside = std::nullopt;
+        }
         result.clips_same_type = !bits.suppress_clipping_same_type;
 
         return result;
@@ -471,6 +482,13 @@ public:
         return contentflags_from_bits(bits);
     }
 
+    contentflags_t set_detail(const contentflags_t &original) const override
+    {
+        auto bits = contentflags_to_bits(original);
+        bits.detail = true;
+        return contentflags_from_bits(bits);
+    }
+
     bool contents_are_type_equal(const contentflags_t &self, const contentflags_t &other) const override
     {
         // fixme-brushbsp: document what this is supposed to do, remove if unneeded?
@@ -1126,6 +1144,13 @@ struct gamedef_q2_t : public gamedef_t
         return result;
     }
 
+    contentflags_t set_detail(const contentflags_t &original) const override
+    {
+        contentflags_t result = original;
+        result.native |= Q2_CONTENTS_DETAIL;
+        return result;
+    }
+
     bool contents_are_type_equal(const contentflags_t &self, const contentflags_t &other) const override
     {
         return self.illusionary_visblocker == other.illusionary_visblocker &&
diff --git a/include/common/bspfile.hh b/include/common/bspfile.hh
index bf008470..a0a96e24 100644
--- a/include/common/bspfile.hh
+++ b/include/common/bspfile.hh
@@ -278,6 +278,7 @@ struct gamedef_t
     virtual contentflags_t create_detail_wall_contents(const contentflags_t &original) const = 0;
     virtual contentflags_t create_detail_solid_contents(const contentflags_t &original) const = 0;
     virtual contentflags_t clear_detail(const contentflags_t &original) const = 0;
+    virtual contentflags_t set_detail(const contentflags_t &original) const = 0;
     virtual bool contents_are_type_equal(const contentflags_t &self, const contentflags_t &other) const = 0;
     virtual bool contents_are_equal(const contentflags_t &self, const contentflags_t &other) const = 0;
     virtual bool contents_are_any_detail(const contentflags_t &contents) const = 0;
diff --git a/qbsp/map.cc b/qbsp/map.cc
index 3d3a866d..bfba543e 100644
--- a/qbsp/map.cc
+++ b/qbsp/map.cc
@@ -2473,6 +2473,13 @@ static contentflags_t Brush_GetContents(const mapentity_t &entity, const mapbrus
     base_contents.illusionary_visblocker =
         string_iequals(entity.epairs.get("classname"), "func_illusionary_visblocker");
 
+    // non-Q2: -transwater implies liquids are detail
+    if (qbsp_options.target_game->id != GAME_QUAKE_II && qbsp_options.transwater.value()) {
+        if (base_contents.is_liquid(qbsp_options.target_game)) {
+            base_contents = qbsp_options.target_game->set_detail(base_contents);
+        }
+    }
+
     return base_contents;
 }
 
diff --git a/testmaps/q1_liquid_is_detail.map b/testmaps/q1_liquid_is_detail.map
new file mode 100644
index 00000000..1927215b
--- /dev/null
+++ b/testmaps/q1_liquid_is_detail.map
@@ -0,0 +1,275 @@
+// Game: Quake
+// Format: Valve
+// entity 0
+{
+"mapversion" "220"
+"classname" "worldspawn"
+"wad" "deprecated/free_wad.wad;deprecated/hintskip.wad"
+// brush 0
+{
+( 184 112 168 ) ( 184 -432 168 ) ( 184 112 -64 ) bolt17 [ 0 1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( 192 -432 -64 ) ( 184 -432 -64 ) ( 192 -432 168 ) bolt17 [ 1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( 192 112 -64 ) ( 184 112 -64 ) ( 192 -432 -64 ) bolt17 [ -1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( 192 -432 168 ) ( 184 -432 168 ) ( 192 112 168 ) bolt17 [ 1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( 192 112 168 ) ( 184 112 168 ) ( 192 112 -64 ) bolt17 [ -1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( 192 -432 168 ) ( 192 112 168 ) ( 192 -432 -64 ) bolt17 [ 0 1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+}
+// brush 1
+{
+( -168 112 168 ) ( -168 104 168 ) ( -168 112 -64 ) bolt17 [ 0 -1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( 184 104 168 ) ( 184 104 -64 ) ( -168 104 168 ) bolt17 [ -1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -168 112 -64 ) ( -168 104 -64 ) ( 184 112 -64 ) bolt17 [ -1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( 184 112 168 ) ( 184 104 168 ) ( -168 112 168 ) bolt17 [ 1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( 184 112 168 ) ( -168 112 168 ) ( 184 112 -64 ) bolt17 [ -1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( 184 112 -64 ) ( 184 104 -64 ) ( 184 112 168 ) bolt17 [ 0 1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+}
+// brush 2
+{
+( -168 -432 -64 ) ( -168 -424 -64 ) ( -168 -432 168 ) bolt17 [ 0 -1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( 184 -432 -64 ) ( -168 -432 -64 ) ( 184 -432 168 ) bolt17 [ 1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( 184 -432 -64 ) ( 184 -424 -64 ) ( -168 -432 -64 ) bolt17 [ -1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( -168 -432 168 ) ( -168 -424 168 ) ( 184 -432 168 ) bolt17 [ 1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( -168 -424 -64 ) ( 184 -424 -64 ) ( -168 -424 168 ) bolt17 [ 1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( 184 -432 168 ) ( 184 -424 168 ) ( 184 -432 -64 ) bolt17 [ 0 1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+}
+// brush 3
+{
+( -168 -424 168 ) ( -168 -424 160 ) ( -168 104 168 ) bolt17 [ 0 -1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( 184 -424 168 ) ( 184 -424 160 ) ( -168 -424 168 ) bolt17 [ 1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( 184 104 160 ) ( -168 104 160 ) ( 184 -424 160 ) bolt17 [ 1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( 184 104 168 ) ( 184 -424 168 ) ( -168 104 168 ) bolt17 [ 1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( -168 104 168 ) ( -168 104 160 ) ( 184 104 168 ) bolt17 [ -1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( 184 104 168 ) ( 184 104 160 ) ( 184 -424 168 ) bolt17 [ 0 1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+}
+// brush 4
+{
+( -168 104 -64 ) ( -168 104 -56 ) ( -168 -424 -64 ) bolt17 [ 0 -1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -168 -424 -64 ) ( -168 -424 -56 ) ( 184 -424 -64 ) bolt17 [ 1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -168 104 -64 ) ( -168 -424 -64 ) ( 184 104 -64 ) bolt17 [ -1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( -168 -424 -56 ) ( -168 104 -56 ) ( 184 -424 -56 ) bolt17 [ -1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( 184 104 -64 ) ( 184 104 -56 ) ( -168 104 -64 ) bolt17 [ -1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( 184 -424 -64 ) ( 184 -424 -56 ) ( 184 104 -64 ) bolt17 [ 0 1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+}
+// brush 5
+{
+( -304 104 -48 ) ( -304 104 -40 ) ( -304 -424 -48 ) *swater4 [ 0 -1 0 0 ] [ 0 0 -1 48 ] 0 1 1
+( -168 -424 -48 ) ( -168 -424 -40 ) ( 184 -424 -48 ) *swater4 [ 1 0 0 0 ] [ 0 0 -1 48 ] 0 1 1
+( -168 104 -56 ) ( -168 -424 -56 ) ( 184 104 -56 ) *swater4 [ -1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( -168 -424 48 ) ( -168 104 48 ) ( 184 -424 48 ) *swater4 [ -1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( 184 104 -48 ) ( 184 104 -40 ) ( -168 104 -48 ) *swater4 [ -1 0 0 0 ] [ 0 0 -1 48 ] 0 1 1
+( 184 -424 -48 ) ( 184 -424 -40 ) ( 184 104 -48 ) *swater4 [ 0 1 0 0 ] [ 0 0 -1 48 ] 0 1 1
+}
+// brush 6
+{
+( -176 -432 -64 ) ( -176 112 -64 ) ( -176 -432 168 ) bolt17 [ 0 -1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -168 -320 0 ) ( -168 -320 16 ) ( -40 -320 16 ) bolt17 [ 1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -176 -432 -64 ) ( -168 -432 -64 ) ( -176 112 -64 ) bolt17 [ -1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( -168 -384 -32 ) ( -168 -368 -32 ) ( -40 -368 -32 ) bolt17 [ 1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( -176 112 -64 ) ( -168 112 -64 ) ( -176 112 168 ) bolt17 [ -1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -168 -432 -64 ) ( -168 -432 168 ) ( -168 112 -64 ) bolt17 [ 0 -1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+}
+// brush 7
+{
+( -176 -432 -64 ) ( -176 112 -64 ) ( -176 -432 168 ) bolt17 [ 0 -1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -168 -320 0 ) ( -168 -320 16 ) ( -40 -320 16 ) bolt17 [ 1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -168 -384 -32 ) ( -40 -368 -32 ) ( -168 -368 -32 ) bolt17 [ -1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( -168 -384 32 ) ( -168 -368 32 ) ( -40 -368 32 ) bolt17 [ 1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( -176 112 -64 ) ( -168 112 -64 ) ( -176 112 168 ) bolt17 [ -1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -168 -432 -64 ) ( -168 -432 168 ) ( -168 112 -64 ) bolt17 [ 0 -1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+}
+// brush 8
+{
+( -176 -432 -64 ) ( -176 112 -64 ) ( -176 -432 168 ) bolt17 [ 0 -1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -168 -384 -16 ) ( -168 -384 0 ) ( -40 -384 0 ) bolt17 [ 1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -176 -432 -64 ) ( -168 -432 -64 ) ( -176 112 -64 ) bolt17 [ -1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( -168 -384 -32 ) ( -168 -368 -32 ) ( -40 -368 -32 ) bolt17 [ 1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( -168 -320 0 ) ( -40 -320 16 ) ( -168 -320 16 ) bolt17 [ -1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -168 -432 -64 ) ( -168 -432 168 ) ( -168 112 -64 ) bolt17 [ 0 -1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+}
+// brush 9
+{
+( -304 -432 -64 ) ( -304 112 -64 ) ( -304 -432 168 ) bolt17 [ 0 -1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -296 -384 -16 ) ( -296 -384 0 ) ( -168 -384 0 ) bolt17 [ 1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -296 -384 -32 ) ( -168 -368 -32 ) ( -296 -368 -32 ) bolt17 [ -1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( -296 -384 32 ) ( -296 -368 32 ) ( -168 -368 32 ) bolt17 [ 1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( -296 -320 0 ) ( -168 -320 16 ) ( -296 -320 16 ) bolt17 [ -1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -296 -432 -64 ) ( -296 -432 168 ) ( -296 112 -64 ) bolt17 [ 0 -1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+}
+// brush 10
+{
+( -176 -432 -64 ) ( -176 112 -64 ) ( -176 -432 168 ) bolt17 [ 0 -1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -168 -384 -16 ) ( -168 -384 0 ) ( -40 -384 0 ) bolt17 [ 1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -168 -384 32 ) ( -40 -368 32 ) ( -168 -368 32 ) bolt17 [ -1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( -176 112 168 ) ( -168 112 168 ) ( -176 -432 168 ) bolt17 [ 1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( -168 -320 0 ) ( -40 -320 16 ) ( -168 -320 16 ) bolt17 [ -1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -168 -432 -64 ) ( -168 -432 168 ) ( -168 112 -64 ) bolt17 [ 0 -1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+}
+// brush 11
+{
+( -176 -432 -64 ) ( -176 112 -64 ) ( -176 -432 168 ) bolt17 [ 0 -1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -176 -432 168 ) ( -168 -432 168 ) ( -176 -432 -64 ) bolt17 [ 1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -176 -432 -64 ) ( -168 -432 -64 ) ( -176 112 -64 ) bolt17 [ -1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( -168 -384 -32 ) ( -168 -368 -32 ) ( -40 -368 -32 ) bolt17 [ 1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( -168 -384 -16 ) ( -40 -384 0 ) ( -168 -384 0 ) bolt17 [ -1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -168 -432 -64 ) ( -168 -432 168 ) ( -168 112 -64 ) bolt17 [ 0 -1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+}
+// brush 12
+{
+( -176 -432 -64 ) ( -176 112 -64 ) ( -176 -432 168 ) bolt17 [ 0 -1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -176 -432 168 ) ( -168 -432 168 ) ( -176 -432 -64 ) bolt17 [ 1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -168 -384 -32 ) ( -40 -368 -32 ) ( -168 -368 -32 ) bolt17 [ -1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( -168 -384 32 ) ( -168 -368 32 ) ( -40 -368 32 ) bolt17 [ 1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( -168 -384 -16 ) ( -40 -384 0 ) ( -168 -384 0 ) bolt17 [ -1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -168 -432 -64 ) ( -168 -432 168 ) ( -168 112 -64 ) bolt17 [ 0 -1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+}
+// brush 13
+{
+( -176 -432 -64 ) ( -176 112 -64 ) ( -176 -432 168 ) bolt17 [ 0 -1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -176 -432 168 ) ( -168 -432 168 ) ( -176 -432 -64 ) bolt17 [ 1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -168 -384 32 ) ( -40 -368 32 ) ( -168 -368 32 ) bolt17 [ -1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( -176 112 168 ) ( -168 112 168 ) ( -176 -432 168 ) bolt17 [ 1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( -168 -384 -16 ) ( -40 -384 0 ) ( -168 -384 0 ) bolt17 [ -1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -168 -432 -64 ) ( -168 -432 168 ) ( -168 112 -64 ) bolt17 [ 0 -1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+}
+// brush 14
+{
+( -304 -432 -64 ) ( -304 112 -64 ) ( -304 -432 168 ) bolt17 [ 0 -1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -296 -320 0 ) ( -296 -320 16 ) ( -168 -320 16 ) bolt17 [ -1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -296 -384 -32 ) ( -168 -368 -32 ) ( -296 -368 -32 ) bolt17 [ -1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( -296 -384 32 ) ( -296 -368 32 ) ( -168 -368 32 ) bolt17 [ 1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( -296 -312 0 ) ( -168 -312 16 ) ( -296 -312 16 ) bolt17 [ -1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -176 -432 -64 ) ( -176 -432 168 ) ( -176 112 -64 ) bolt17 [ 0 -1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+}
+// brush 15
+{
+( -304 -432 -64 ) ( -304 112 -64 ) ( -304 -432 168 ) bolt17 [ 0 -1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -296 -392 -16 ) ( -296 -392 0 ) ( -168 -392 0 ) bolt17 [ 1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -296 -384 -32 ) ( -168 -368 -32 ) ( -296 -368 -32 ) bolt17 [ -1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( -296 -384 32 ) ( -296 -368 32 ) ( -168 -368 32 ) bolt17 [ 1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( -296 -384 -16 ) ( -168 -384 0 ) ( -296 -384 0 ) bolt17 [ 1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -176 -432 -64 ) ( -176 -432 168 ) ( -176 112 -64 ) bolt17 [ 0 -1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+}
+// brush 16
+{
+( -304 -432 -64 ) ( -304 112 -64 ) ( -304 -432 168 ) bolt17 [ 0 -1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -296 -384 -16 ) ( -296 -384 0 ) ( -168 -384 0 ) bolt17 [ 1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -296 -384 32 ) ( -168 -368 32 ) ( -296 -368 32 ) bolt17 [ 1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( -296 -384 40 ) ( -296 -368 40 ) ( -168 -368 40 ) bolt17 [ 1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( -296 -320 0 ) ( -168 -320 16 ) ( -296 -320 16 ) bolt17 [ -1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -176 -432 -64 ) ( -176 -432 168 ) ( -176 112 -64 ) bolt17 [ 0 -1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+}
+// brush 17
+{
+( -304 -432 -64 ) ( -304 112 -64 ) ( -304 -432 168 ) bolt17 [ 0 -1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -296 -384 -16 ) ( -296 -384 0 ) ( -168 -384 0 ) bolt17 [ 1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -296 -384 -40 ) ( -168 -368 -40 ) ( -296 -368 -40 ) bolt17 [ -1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( -296 -384 -32 ) ( -296 -368 -32 ) ( -168 -368 -32 ) bolt17 [ -1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( -296 -320 0 ) ( -168 -320 16 ) ( -296 -320 16 ) bolt17 [ -1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -176 -432 -64 ) ( -176 -432 168 ) ( -176 112 -64 ) bolt17 [ 0 -1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+}
+// brush 18
+{
+( -304 -112 64 ) ( -304 432 64 ) ( -304 -112 296 ) bolt17 [ 0 -1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -296 -64 112 ) ( -296 -64 128 ) ( -168 -64 128 ) bolt17 [ 1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -296 -64 160 ) ( -168 -48 160 ) ( -296 -48 160 ) bolt17 [ 1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( -296 -64 168 ) ( -296 -48 168 ) ( -168 -48 168 ) bolt17 [ 1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( -296 0 128 ) ( -168 0 144 ) ( -296 0 144 ) bolt17 [ -1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -176 -112 64 ) ( -176 -112 296 ) ( -176 432 64 ) bolt17 [ 0 -1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+}
+// brush 19
+{
+( -304 -112 64 ) ( -304 432 64 ) ( -304 -112 296 ) bolt17 [ 0 -1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -296 -72 112 ) ( -296 -72 128 ) ( -168 -72 128 ) bolt17 [ 1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -296 -64 96 ) ( -168 -48 96 ) ( -296 -48 96 ) bolt17 [ -1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( -296 -64 160 ) ( -296 -48 160 ) ( -168 -48 160 ) bolt17 [ 1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( -296 -64 112 ) ( -168 -64 128 ) ( -296 -64 128 ) bolt17 [ 1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -176 -112 64 ) ( -176 -112 296 ) ( -176 432 64 ) bolt17 [ 0 -1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+}
+// brush 20
+{
+( -304 -112 64 ) ( -304 432 64 ) ( -304 -112 296 ) bolt17 [ 0 -1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -296 -64 112 ) ( -296 -64 128 ) ( -168 -64 128 ) bolt17 [ 1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -296 -64 96 ) ( -168 -48 96 ) ( -296 -48 96 ) bolt17 [ -1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( -296 -64 160 ) ( -296 -48 160 ) ( -168 -48 160 ) bolt17 [ 1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( -296 0 128 ) ( -168 0 144 ) ( -296 0 144 ) bolt17 [ -1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -296 -112 64 ) ( -296 -112 296 ) ( -296 432 64 ) bolt17 [ 0 -1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+}
+// brush 21
+{
+( -304 -112 64 ) ( -304 432 64 ) ( -304 -112 296 ) bolt17 [ 0 -1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -296 0 128 ) ( -296 0 144 ) ( -168 0 144 ) bolt17 [ -1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -296 -64 96 ) ( -168 -48 96 ) ( -296 -48 96 ) bolt17 [ -1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( -296 -64 160 ) ( -296 -48 160 ) ( -168 -48 160 ) bolt17 [ 1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( -296 8 128 ) ( -168 8 144 ) ( -296 8 144 ) bolt17 [ -1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -176 -112 64 ) ( -176 -112 296 ) ( -176 432 64 ) bolt17 [ 0 -1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+}
+// brush 22
+{
+( -304 -112 64 ) ( -304 432 64 ) ( -304 -112 296 ) bolt17 [ 0 -1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -296 -64 112 ) ( -296 -64 128 ) ( -168 -64 128 ) bolt17 [ 1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -296 -64 88 ) ( -168 -48 88 ) ( -296 -48 88 ) bolt17 [ -1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( -296 -64 96 ) ( -296 -48 96 ) ( -168 -48 96 ) bolt17 [ -1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( -296 0 128 ) ( -168 0 144 ) ( -296 0 144 ) bolt17 [ -1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -176 -112 64 ) ( -176 -112 296 ) ( -176 432 64 ) bolt17 [ 0 -1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+}
+// brush 23
+{
+( -176 -432 -64 ) ( -176 112 -64 ) ( -176 -432 168 ) bolt17 [ 0 -1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -168 0 72 ) ( -168 0 96 ) ( -40 0 96 ) bolt17 [ 1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -168 -384 32 ) ( -40 -368 32 ) ( -168 -368 32 ) bolt17 [ -1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( -168 -64 96 ) ( -168 -40 96 ) ( -40 -40 96 ) bolt17 [ 1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( -176 112 -64 ) ( -168 112 -64 ) ( -176 112 168 ) bolt17 [ -1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -168 -432 -64 ) ( -168 -432 168 ) ( -168 112 -64 ) bolt17 [ 0 -1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+}
+// brush 24
+{
+( -176 -432 -64 ) ( -176 112 -64 ) ( -176 -432 168 ) bolt17 [ 0 -1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -168 0 72 ) ( -168 0 96 ) ( -40 0 96 ) bolt17 [ 1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -168 -64 96 ) ( -40 -40 96 ) ( -168 -40 96 ) bolt17 [ -1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( -176 112 168 ) ( -168 112 168 ) ( -176 -432 168 ) bolt17 [ 1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( -176 112 -64 ) ( -168 112 -64 ) ( -176 112 168 ) bolt17 [ -1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -168 -432 -64 ) ( -168 -432 168 ) ( -168 112 -64 ) bolt17 [ 0 -1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+}
+// brush 25
+{
+( -176 -432 -64 ) ( -176 112 -64 ) ( -176 -432 168 ) bolt17 [ 0 -1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -168 -64 120 ) ( -168 -64 136 ) ( -40 -64 136 ) bolt17 [ 1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -168 -384 32 ) ( -40 -368 32 ) ( -168 -368 32 ) bolt17 [ -1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( -168 -64 96 ) ( -168 -40 96 ) ( -40 -40 96 ) bolt17 [ 1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( -168 0 72 ) ( -40 0 96 ) ( -168 0 96 ) bolt17 [ -1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -168 -432 -64 ) ( -168 -432 168 ) ( -168 112 -64 ) bolt17 [ 0 -1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+}
+// brush 26
+{
+( -176 -432 -64 ) ( -176 112 -64 ) ( -176 -432 168 ) bolt17 [ 0 -1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -168 -320 0 ) ( -168 -320 16 ) ( -40 -320 16 ) bolt17 [ 1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -168 -384 32 ) ( -40 -368 32 ) ( -168 -368 32 ) bolt17 [ -1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( -168 -64 96 ) ( -168 -40 96 ) ( -40 -40 96 ) bolt17 [ 1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( -168 -64 120 ) ( -40 -64 136 ) ( -168 -64 136 ) bolt17 [ -1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -168 -432 -64 ) ( -168 -432 168 ) ( -168 112 -64 ) bolt17 [ 0 -1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+}
+// brush 27
+{
+( -176 -432 -64 ) ( -176 112 -64 ) ( -176 -432 168 ) bolt17 [ 0 -1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -168 -320 0 ) ( -168 -320 16 ) ( -40 -320 16 ) bolt17 [ 1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -168 -64 96 ) ( -40 -40 96 ) ( -168 -40 96 ) bolt17 [ -1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( -176 112 168 ) ( -168 112 168 ) ( -176 -432 168 ) bolt17 [ 1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( -168 -64 120 ) ( -40 -64 136 ) ( -168 -64 136 ) bolt17 [ -1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -168 -432 -64 ) ( -168 -432 168 ) ( -168 112 -64 ) bolt17 [ 0 -1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+}
+// brush 28
+{
+( -176 -432 -64 ) ( -176 112 -64 ) ( -176 -432 168 ) bolt17 [ 0 -1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -168 -64 120 ) ( -168 -64 136 ) ( -40 -64 136 ) bolt17 [ -1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -168 -64 160 ) ( -40 -40 160 ) ( -168 -40 160 ) bolt17 [ -1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( -176 112 168 ) ( -168 112 168 ) ( -176 -432 168 ) bolt17 [ 1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( -168 0 120 ) ( -40 0 136 ) ( -168 0 136 ) bolt17 [ -1 0 0 0 ] [ 0 0 -1 32 ] 0 1 1
+( -168 -432 -64 ) ( -168 -432 168 ) ( -168 112 -64 ) bolt17 [ 0 -1 0 0 ] [ 0 0 -1 32 ] 0 1 1
+}
+}
+// entity 1
+{
+"classname" "info_player_start"
+"origin" "-96 -304 -24"
+"angle" "90"
+}
diff --git a/tests/test_qbsp.cc b/tests/test_qbsp.cc
index 6e672055..979d85fe 100644
--- a/tests/test_qbsp.cc
+++ b/tests/test_qbsp.cc
@@ -2324,3 +2324,46 @@ TEST_CASE("q1_tjunc_matrix")
         CHECK( has_tjunc(INDEX_SKY, INDEX_SKY));
     }
 }
+
+TEST_CASE("q1_liquid_is_detail" * doctest::test_suite("testmaps_q1"))
+{
+    const auto portal_underwater = prtfile_winding_t{{-168, -384, 32}, {-168, -320, 32}, {-168, -320, -32}, {-168, -384, -32}};
+    const auto portal_above = portal_underwater.translate({0, 320, 128});
+
+    SUBCASE("transparent water") {
+        // by default, we're compiling with transparent water
+        // this implies water is detail
+
+        const auto [bsp, bspx, prt] = LoadTestmapQ1("q1_liquid_is_detail.map");
+
+        REQUIRE(prt.has_value());
+        REQUIRE(2 == prt->portals.size());
+
+        CHECK(((PortalMatcher(prt->portals[0].winding, portal_underwater) && PortalMatcher(prt->portals[1].winding, portal_above)) ||
+               (PortalMatcher(prt->portals[0].winding, portal_above) && PortalMatcher(prt->portals[1].winding, portal_underwater))));
+
+        // only 3 clusters: room with water, side corridors
+        CHECK(prt->portalleafs == 3);
+
+        // above water, in water, plus 2 side rooms.
+        // note
+        CHECK(prt->portalleafs_real == 4);
+    }
+
+    SUBCASE("opaque water") {
+        const auto [bsp, bspx, prt] = LoadTestmapQ1("q1_liquid_is_detail.map", {"-notranswater"});
+
+        REQUIRE(prt.has_value());
+        REQUIRE(2 == prt->portals.size());
+
+        // same portals as transparent water case
+        // (since the water is opqaue, it doesn't get a portal)
+        CHECK(((PortalMatcher(prt->portals[0].winding, portal_underwater) && PortalMatcher(prt->portals[1].winding, portal_above)) ||
+               (PortalMatcher(prt->portals[0].winding, portal_above) && PortalMatcher(prt->portals[1].winding, portal_underwater))));
+
+        // 4 clusters this time:
+        // above water, in water, plus 2 side rooms.
+        CHECK(prt->portalleafs == 4);
+        CHECK(prt->portalleafs_real == 4);
+    }
+}