diff --git a/common/main/segnum.h b/common/main/segnum.h
index dfd1f5acb..ff6b2260d 100644
--- a/common/main/segnum.h
+++ b/common/main/segnum.h
@@ -1,8 +1,8 @@
 #pragma once
 #include "strictindex.h"
 
-DEFINE_STRICT_INDEX_NUMBER(int16_t, segnum_t);
-DEFINE_STRICT_INDEX_CONSTANT_TYPE(segment_magic_constant_t, segnum_t, int16_t);
-DEFINE_STRICT_INDEX_CONSTANT_NUMBER(segment_magic_constant_t, -2, segment_exit);
-DEFINE_STRICT_INDEX_CONSTANT_NUMBER(segment_magic_constant_t, -1, segment_none);
+DEFINE_STRICT_INDEX_NUMBER(uint16_t, segnum_t);
+DEFINE_STRICT_INDEX_CONSTANT_TYPE(segment_magic_constant_t, segnum_t, uint16_t);
+DEFINE_STRICT_INDEX_CONSTANT_NUMBER(segment_magic_constant_t, 0xfffe, segment_exit);
+DEFINE_STRICT_INDEX_CONSTANT_NUMBER(segment_magic_constant_t, 0xffff, segment_none);
 DEFINE_STRICT_INDEX_CONSTANT_NUMBER(segment_magic_constant_t, 0, segment_first);
diff --git a/common/main/switch.h b/common/main/switch.h
index adf125e48..060169a1d 100644
--- a/common/main/switch.h
+++ b/common/main/switch.h
@@ -74,7 +74,7 @@ struct v29_trigger
 	fix     time;
 	sbyte   link_num;
 	short   num_links;
-	array<short, MAX_WALLS_PER_LINK>   seg;
+	array<segnum_t, MAX_WALLS_PER_LINK>   seg;
 	array<short, MAX_WALLS_PER_LINK>   side;
 } __pack__;
 
@@ -85,7 +85,7 @@ struct v30_trigger
 	sbyte   pad;                        //keep alignment
 	fix     value;
 	fix     time;
-	array<short, MAX_WALLS_PER_LINK>   seg;
+	array<segnum_t, MAX_WALLS_PER_LINK>   seg;
 	array<short, MAX_WALLS_PER_LINK>   side;
 } __pack__;
 #endif
diff --git a/similar/main/ai.cpp b/similar/main/ai.cpp
index 075705924..a213b1318 100644
--- a/similar/main/ai.cpp
+++ b/similar/main/ai.cpp
@@ -2158,7 +2158,7 @@ static void teleport_boss(const vobjptridx_t objp)
 	//	Pick a random segment from the list of boss-teleportable-to segments.
 	rand_index = (d_rand() * Boss_teleport_segs.count()) >> 15;
 	rand_segnum = Boss_teleport_segs[rand_index];
-	Assert((rand_segnum >= 0) && (rand_segnum <= Highest_segment_index));
+	Assert(rand_segnum <= Highest_segment_index);
 
 	if (Game_mode & GM_MULTI)
 		multi_send_boss_teleport(objp, rand_segnum);
diff --git a/similar/main/fvi.cpp b/similar/main/fvi.cpp
index 43cbe3a89..681c5fb56 100644
--- a/similar/main/fvi.cpp
+++ b/similar/main/fvi.cpp
@@ -633,9 +633,6 @@ int find_vector_intersection(const fvi_query &fq, fvi_info &hit_data)
 	int hit_type;
 	segnum_t hit_seg2;
 	vms_vector hit_pnt;
-
-	Assert(fq.startseg <= Highest_segment_index && fq.startseg >= 0);
-
 	fvi_hit_seg = segment_none;
 	fvi_hit_side = -1;
 
@@ -645,9 +642,9 @@ int find_vector_intersection(const fvi_query &fq, fvi_info &hit_data)
 	//Assert(check_point_in_seg(p0,startseg,0).centermask==0);	//start point not in seg
 
 	// invalid segnum, so say there is no hit.
-	if(fq.startseg < 0 || fq.startseg > Highest_segment_index)
+	if(fq.startseg > Highest_segment_index)
 	{
-
+		Assert(fq.startseg <= Highest_segment_index);
 		hit_data.hit_type = HIT_BAD_P0;
 		hit_data.hit_pnt = *fq.p0;
 		hit_data.hit_seg = hit_data.hit_side = hit_data.hit_object = 0;
diff --git a/similar/main/gameseg.cpp b/similar/main/gameseg.cpp
index 393500d12..a19165c3c 100644
--- a/similar/main/gameseg.cpp
+++ b/similar/main/gameseg.cpp
@@ -1647,11 +1647,11 @@ static void change_light(const vsegptridx_t segnum, int sidenum, int dir)
 				for (int k=0; k<4; k++) {
 					fix	dl,new_l;
 					dl = dir * j.vert_light[k] * DL_SCALE;
-					Assert(j.segnum >= 0 && j.segnum <= Highest_segment_index);
 					Assert(j.sidenum >= 0 && j.sidenum < MAX_SIDES_PER_SEGMENT);
-					new_l = (Segments[j.segnum].sides[j.sidenum].uvls[k].l += dl);
+					const auto &&segp = vsegptr(j.segnum);
+					new_l = (segp->sides[j.sidenum].uvls[k].l += dl);
 					if (new_l < 0)
-						Segments[j.segnum].sides[j.sidenum].uvls[k].l = 0;
+						segp->sides[j.sidenum].uvls[k].l = 0;
 				}
 			}
 		}