diff --git a/common/bspfile.cc b/common/bspfile.cc
index 9957615f..906f8a7a 100644
--- a/common/bspfile.cc
+++ b/common/bspfile.cc
@@ -621,6 +621,9 @@ public:
         if (contents_are_solid(a) || contents_are_solid(b)) {
             return create_solid_contents();
         }
+        if (contents_are_sky(a) || contents_are_sky(b)) {
+            return contentflags_t{CONTENTS_SKY};
+        }
 
         return contentflags_from_bits(bits_a | bits_b);
     }
diff --git a/testmaps/q1_sealing_contents.map b/testmaps/q1_sealing_contents.map
new file mode 100644
index 00000000..90494859
--- /dev/null
+++ b/testmaps/q1_sealing_contents.map
@@ -0,0 +1,162 @@
+// Game: Quake
+// Format: Valve
+// entity 0
+{
+"mapversion" "220"
+"classname" "worldspawn"
+"wad" "deprecated/free_wad.wad;deprecated/fence.wad;deprecated/origin.wad;deprecated/hintskip.wad"
+"_wateralpha" "0.5"
+"_tb_def" "builtin:Quake.fgd"
+// brush 0
+{
+( -144 -192 48 ) ( -144 32 48 ) ( -144 -192 208 ) orangestuff8 [ 0 1 0 16 ] [ 0 0 -1 48 ] 0 1 1
+( -144 -640 208 ) ( -128 -640 208 ) ( -144 -640 48 ) orangestuff8 [ -1 0 0 -16 ] [ 0 0 -1 48 ] 180 1 1
+( -144 -192 48 ) ( -128 -192 48 ) ( -144 32 48 ) orangestuff8 [ 1 0 0 16 ] [ 0 -1 0 -16 ] 180 1 1
+( -144 32 336 ) ( -128 32 336 ) ( -144 -192 336 ) orangestuff8 [ -1 0 0 -16 ] [ 0 -1 0 -16 ] 180 1 1
+( -144 32 48 ) ( -128 32 48 ) ( -144 32 208 ) orangestuff8 [ 1 0 0 16 ] [ 0 0 -1 48 ] 180 1 1
+( -128 -192 48 ) ( -128 -192 208 ) ( -128 32 48 ) orangestuff8 [ 0 1 0 16 ] [ 0 0 -1 48 ] 0 1 1
+}
+// brush 1
+{
+( -128 32 208 ) ( -128 16 208 ) ( -128 32 48 ) orangestuff8 [ 0 1 0 16 ] [ 0 0 -1 48 ] 0 1 1
+( 96 16 208 ) ( 96 16 48 ) ( -128 16 208 ) orangestuff8 [ 1 0 0 16 ] [ 0 0 -1 48 ] 180 1 1
+( -128 32 48 ) ( -128 16 48 ) ( 96 32 48 ) orangestuff8 [ 1 0 0 16 ] [ 0 -1 0 -16 ] 180 1 1
+( 96 32 336 ) ( 96 16 336 ) ( -128 32 336 ) orangestuff8 [ -1 0 0 -16 ] [ 0 -1 0 -16 ] 180 1 1
+( 96 32 208 ) ( -128 32 208 ) ( 96 32 48 ) orangestuff8 [ 1 0 0 16 ] [ 0 0 -1 48 ] 180 1 1
+( 464 32 48 ) ( 464 16 48 ) ( 464 32 208 ) orangestuff8 [ 0 -1 0 -16 ] [ 0 0 -1 48 ] 0 1 1
+}
+// brush 2
+{
+( -128 -656 48 ) ( -128 -640 48 ) ( -128 -656 208 ) orangestuff8 [ 0 1 0 -32 ] [ 0 0 -1 48 ] 0 1 1
+( 464 -656 48 ) ( 240 -656 48 ) ( 464 -656 208 ) orangestuff8 [ -1 0 0 32 ] [ 0 0 -1 48 ] 180 1 1
+( 464 -656 48 ) ( 464 -640 48 ) ( 240 -656 48 ) orangestuff8 [ 1 0 0 -32 ] [ 0 -1 0 32 ] 180 1 1
+( 240 -656 336 ) ( 240 -640 336 ) ( 464 -656 336 ) orangestuff8 [ -1 0 0 32 ] [ 0 -1 0 32 ] 180 1 1
+( 240 -640 48 ) ( 464 -640 48 ) ( 240 -640 208 ) orangestuff8 [ -1 0 0 32 ] [ 0 0 -1 48 ] 180 1 1
+( 464 -656 208 ) ( 464 -640 208 ) ( 464 -656 48 ) orangestuff8 [ 0 -1 0 32 ] [ 0 0 -1 48 ] 0 1 1
+}
+// brush 3
+{
+( -128 -176 352 ) ( -128 -176 336 ) ( -128 16 352 ) sky3 [ 0 1 0 16 ] [ 0 0 -1 64 ] 0 1 1
+( 96 -640 352 ) ( 96 -640 336 ) ( -128 -640 352 ) sky3 [ -1 0 0 -16 ] [ 0 0 -1 64 ] 180 1 1
+( 96 16 336 ) ( -128 16 336 ) ( 96 -176 336 ) sky3 [ -1 0 0 -16 ] [ 0 -1 0 -16 ] 180 1 1
+( 96 16 352 ) ( 96 -176 352 ) ( -128 16 352 ) sky3 [ -1 0 0 -16 ] [ 0 -1 0 -16 ] 180 1 1
+( -128 16 352 ) ( -128 16 336 ) ( 96 16 352 ) sky3 [ 1 0 0 16 ] [ 0 0 -1 64 ] 180 1 1
+( 464 16 352 ) ( 464 16 336 ) ( 464 -176 352 ) sky3 [ 0 -1 0 -16 ] [ 0 0 -1 64 ] 0 1 1
+}
+// brush 4
+{
+( -128 16 48 ) ( -128 16 64 ) ( -128 -176 48 ) orangestuff8 [ 0 1 0 16 ] [ 0 0 -1 48 ] 0 1 1
+( -128 -640 48 ) ( -128 -640 64 ) ( 96 -640 48 ) orangestuff8 [ -1 0 0 -16 ] [ 0 0 -1 48 ] 180 1 1
+( -128 16 48 ) ( -128 -176 48 ) ( 96 16 48 ) orangestuff8 [ 1 0 0 16 ] [ 0 -1 0 -16 ] 180 1 1
+( -128 -176 64 ) ( -128 16 64 ) ( 96 -176 64 ) orangestuff8 [ 1 0 0 16 ] [ 0 -1 0 -16 ] 180 1 1
+( 96 16 48 ) ( 96 16 64 ) ( -128 16 48 ) orangestuff8 [ 1 0 0 16 ] [ 0 0 -1 48 ] 180 1 1
+( 464 -176 48 ) ( 464 -176 64 ) ( 464 16 48 ) orangestuff8 [ 0 -1 0 -16 ] [ 0 0 -1 48 ] 0 1 1
+}
+// brush 5
+{
+( 464 -432 208 ) ( 464 -656 208 ) ( 464 -432 48 ) orangestuff8 [ 0 -1 0 32 ] [ 0 0 -1 48 ] 0 1 1
+( 480 -656 48 ) ( 464 -656 48 ) ( 480 -656 208 ) orangestuff8 [ -1 0 0 32 ] [ 0 0 -1 48 ] 180 1 1
+( 480 -432 48 ) ( 464 -432 48 ) ( 480 -656 48 ) orangestuff8 [ 1 0 0 -32 ] [ 0 -1 0 32 ] 180 1 1
+( 480 -656 336 ) ( 464 -656 336 ) ( 480 -432 336 ) orangestuff8 [ -1 0 0 32 ] [ 0 -1 0 32 ] 180 1 1
+( 480 16 208 ) ( 464 16 208 ) ( 480 16 48 ) orangestuff8 [ 1 0 0 -32 ] [ 0 0 -1 48 ] 180 1 1
+( 480 -656 208 ) ( 480 -432 208 ) ( 480 -656 48 ) orangestuff8 [ 0 -1 0 32 ] [ 0 0 -1 48 ] 0 1 1
+}
+}
+// entity 1
+{
+"classname" "info_player_start"
+"origin" "-56 -96 120"
+}
+// entity 2
+{
+"classname" "func_detail"
+// brush 0
+{
+( 272 -576 336 ) ( 272 -575 336 ) ( 272 -576 337 ) bolt1 [ 0 -1 0 0 ] [ 0 0 -1 16 ] 0 1 1
+( 272 -576 336 ) ( 272 -576 337 ) ( 273 -576 336 ) bolt1 [ 1 0 0 0 ] [ 0 0 -1 16 ] 0 1 1
+( 272 -576 320 ) ( 273 -576 320 ) ( 272 -575 320 ) bolt1 [ -1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( 320 -528 352 ) ( 320 -527 352 ) ( 321 -528 352 ) bolt1 [ 1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( 320 -528 352 ) ( 321 -528 352 ) ( 320 -528 353 ) bolt1 [ -1 0 0 0 ] [ 0 0 -1 16 ] 0 1 1
+( 320 -528 352 ) ( 320 -528 353 ) ( 320 -527 352 ) bolt1 [ 0 1 0 0 ] [ 0 0 -1 16 ] 0 1 1
+}
+// brush 1
+{
+( 272 -576 64 ) ( 272 -575 64 ) ( 272 -576 65 ) bolt1 [ 0 -1 0 0 ] [ 0 0 -1 0 ] 0 1 1
+( 272 -576 64 ) ( 272 -576 65 ) ( 273 -576 64 ) bolt1 [ 1 0 0 0 ] [ 0 0 -1 0 ] 0 1 1
+( 272 -576 48 ) ( 273 -576 48 ) ( 272 -575 48 ) bolt1 [ -1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( 320 -528 80 ) ( 320 -527 80 ) ( 321 -528 80 ) bolt1 [ 1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( 320 -528 80 ) ( 321 -528 80 ) ( 320 -528 81 ) bolt1 [ -1 0 0 0 ] [ 0 0 -1 0 ] 0 1 1
+( 320 -528 80 ) ( 320 -528 81 ) ( 320 -527 80 ) bolt1 [ 0 1 0 0 ] [ 0 0 -1 0 ] 0 1 1
+}
+}
+// entity 3
+{
+"classname" "func_detail_illusionary"
+// brush 0
+{
+( 144 -576 336 ) ( 144 -575 336 ) ( 144 -576 337 ) bolt1 [ 0 -1 0 0 ] [ 0 0 -1 16 ] 0 1 1
+( 144 -576 336 ) ( 144 -576 337 ) ( 145 -576 336 ) bolt1 [ 1 0 0 0 ] [ 0 0 -1 16 ] 0 1 1
+( 144 -576 320 ) ( 145 -576 320 ) ( 144 -575 320 ) bolt1 [ -1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( 192 -528 352 ) ( 192 -527 352 ) ( 193 -528 352 ) bolt1 [ 1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( 192 -528 352 ) ( 193 -528 352 ) ( 192 -528 353 ) bolt1 [ -1 0 0 0 ] [ 0 0 -1 16 ] 0 1 1
+( 192 -528 352 ) ( 192 -528 353 ) ( 192 -527 352 ) bolt1 [ 0 1 0 0 ] [ 0 0 -1 16 ] 0 1 1
+}
+// brush 1
+{
+( 144 -576 64 ) ( 144 -575 64 ) ( 144 -576 65 ) bolt1 [ 0 -1 0 0 ] [ 0 0 -1 0 ] 0 1 1
+( 144 -576 64 ) ( 144 -576 65 ) ( 145 -576 64 ) bolt1 [ 1 0 0 0 ] [ 0 0 -1 0 ] 0 1 1
+( 144 -576 48 ) ( 145 -576 48 ) ( 144 -575 48 ) bolt1 [ -1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( 192 -528 80 ) ( 192 -527 80 ) ( 193 -528 80 ) bolt1 [ 1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( 192 -528 80 ) ( 193 -528 80 ) ( 192 -528 81 ) bolt1 [ -1 0 0 0 ] [ 0 0 -1 0 ] 0 1 1
+( 192 -528 80 ) ( 192 -528 81 ) ( 192 -527 80 ) bolt1 [ 0 1 0 0 ] [ 0 0 -1 0 ] 0 1 1
+}
+}
+// entity 4
+{
+"classname" "func_detail_wall"
+// brush 0
+{
+( 208 -576 336 ) ( 208 -575 336 ) ( 208 -576 337 ) bolt1 [ 0 -1 0 0 ] [ 0 0 -1 16 ] 0 1 1
+( 208 -576 336 ) ( 208 -576 337 ) ( 209 -576 336 ) bolt1 [ 1 0 0 0 ] [ 0 0 -1 16 ] 0 1 1
+( 208 -576 320 ) ( 209 -576 320 ) ( 208 -575 320 ) bolt1 [ -1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( 256 -528 352 ) ( 256 -527 352 ) ( 257 -528 352 ) bolt1 [ 1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( 256 -528 352 ) ( 257 -528 352 ) ( 256 -528 353 ) bolt1 [ -1 0 0 0 ] [ 0 0 -1 16 ] 0 1 1
+( 256 -528 352 ) ( 256 -528 353 ) ( 256 -527 352 ) bolt1 [ 0 1 0 0 ] [ 0 0 -1 16 ] 0 1 1
+}
+// brush 1
+{
+( 208 -576 64 ) ( 208 -575 64 ) ( 208 -576 65 ) bolt1 [ 0 -1 0 0 ] [ 0 0 -1 0 ] 0 1 1
+( 208 -576 64 ) ( 208 -576 65 ) ( 209 -576 64 ) bolt1 [ 1 0 0 0 ] [ 0 0 -1 0 ] 0 1 1
+( 208 -576 48 ) ( 209 -576 48 ) ( 208 -575 48 ) bolt1 [ -1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( 256 -528 80 ) ( 256 -527 80 ) ( 257 -528 80 ) bolt1 [ 1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( 256 -528 80 ) ( 257 -528 80 ) ( 256 -528 81 ) bolt1 [ -1 0 0 0 ] [ 0 0 -1 0 ] 0 1 1
+( 256 -528 80 ) ( 256 -528 81 ) ( 256 -527 80 ) bolt1 [ 0 1 0 0 ] [ 0 0 -1 0 ] 0 1 1
+}
+}
+// entity 5
+{
+"classname" "func_group"
+// brush 0
+{
+( 336 -576 336 ) ( 336 -575 336 ) ( 336 -576 337 ) *swater4 [ 0 -1 0 0 ] [ 0 0 -1 16 ] 0 1 1
+( 336 -576 336 ) ( 336 -576 337 ) ( 337 -576 336 ) *swater4 [ 1 0 0 0 ] [ 0 0 -1 16 ] 0 1 1
+( 336 -576 320 ) ( 337 -576 320 ) ( 336 -575 320 ) *swater4 [ -1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( 384 -528 352 ) ( 384 -527 352 ) ( 385 -528 352 ) *swater4 [ 1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( 384 -528 352 ) ( 385 -528 352 ) ( 384 -528 353 ) *swater4 [ -1 0 0 0 ] [ 0 0 -1 16 ] 0 1 1
+( 384 -528 352 ) ( 384 -528 353 ) ( 384 -527 352 ) *swater4 [ 0 1 0 0 ] [ 0 0 -1 16 ] 0 1 1
+}
+// brush 1
+{
+( 336 -576 64 ) ( 336 -575 64 ) ( 336 -576 65 ) *swater4 [ 0 -1 0 0 ] [ 0 0 -1 0 ] 0 1 1
+( 336 -576 64 ) ( 336 -576 65 ) ( 337 -576 64 ) *swater4 [ 1 0 0 0 ] [ 0 0 -1 0 ] 0 1 1
+( 336 -576 48 ) ( 337 -576 48 ) ( 336 -575 48 ) *swater4 [ -1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( 384 -528 80 ) ( 384 -527 80 ) ( 385 -528 80 ) *swater4 [ 1 0 0 0 ] [ 0 -1 0 0 ] 0 1 1
+( 384 -528 80 ) ( 385 -528 80 ) ( 384 -528 81 ) *swater4 [ -1 0 0 0 ] [ 0 0 -1 0 ] 0 1 1
+( 384 -528 80 ) ( 384 -528 81 ) ( 384 -527 80 ) *swater4 [ 0 1 0 0 ] [ 0 0 -1 0 ] 0 1 1
+}
+}
+// entity 6
+{
+"classname" "ambient_drip"
+"origin" "168 -296 200"
+}
diff --git a/tests/test_common.cc b/tests/test_common.cc
index c9462fca..f402fddb 100644
--- a/tests/test_common.cc
+++ b/tests/test_common.cc
@@ -57,10 +57,20 @@ TEST_SUITE("common")
         {
             auto combined = game_q1->combine_contents(detail_solid, contentflags_t{CONTENTS_WATER});
 
+            CHECK(combined.is_any_solid(game_q1));
             CHECK(combined.is_detail_solid(game_q1));
             CHECK(!combined.is_liquid(game_q1));
             CHECK(!combined.is_solid(game_q1));
         }
+
+        SUBCASE("detail_solid plus sky")
+        {
+            auto combined = game_q1->combine_contents(detail_solid, contentflags_t{CONTENTS_SKY});
+
+            CHECK(!combined.is_detail_solid(game_q1));
+            CHECK(combined.is_sky(game_q1));
+            CHECK(!combined.is_solid(game_q1));
+        }
     }
 
     TEST_CASE("shared content flag tests")
diff --git a/tests/test_qbsp.cc b/tests/test_qbsp.cc
index d4cf0de0..41d68098 100644
--- a/tests/test_qbsp.cc
+++ b/tests/test_qbsp.cc
@@ -861,6 +861,13 @@ TEST_CASE("q1_detail_non_sealing" * doctest::test_suite("testmaps_q1"))
     CHECK(!prt.has_value());
 }
 
+TEST_CASE("q1_sealing_contents" * doctest::test_suite("testmaps_q1"))
+{
+    const auto [bsp, bspx, prt] = LoadTestmapQ1("q1_sealing_contents.map");
+
+    CHECK(prt.has_value());
+}
+
 TEST_CASE("detail_doesnt_remove_world_nodes" * doctest::test_suite("testmaps_q1"))
 {
     const auto [bsp, bspx, prt] = LoadTestmapQ1("qbsp_detail_doesnt_remove_world_nodes.map");