diff --git a/common/main/segment.h b/common/main/segment.h
index 7d2fff2a1..8124bf5c7 100644
--- a/common/main/segment.h
+++ b/common/main/segment.h
@@ -203,7 +203,7 @@ struct group
 }
 
 #if defined(DXX_BUILD_DESCENT_I) || defined(DXX_BUILD_DESCENT_II)
-#define Highest_segment_index Segments.highest
+#define Highest_segment_index static_cast<const unsigned &>(Segments.highest)
 
 namespace dsx {
 DEFINE_VALPTRIDX_SUBTYPE(seg, segment, segnum_t, Segments);
diff --git a/similar/editor/segment.cpp b/similar/editor/segment.cpp
index bf2b27530..7bb70aca0 100644
--- a/similar/editor/segment.cpp
+++ b/similar/editor/segment.cpp
@@ -321,7 +321,7 @@ segnum_t get_free_segment_number(void)
 		if (Segments[segnum].segnum == segment_none) {
 			Num_segments++;
 			if (segnum > Highest_segment_index)
-				Highest_segment_index = segnum;
+				Segments.set_count(segnum + 1);
 			return segnum;
 		}
 
@@ -689,7 +689,7 @@ static void compress_segments(void)
 			}	// end if (seg > hole)
 		}	// end if
 
-	Highest_segment_index = Num_segments-1;
+	Segments.set_count(Num_segments);
 	med_create_new_segment_from_cursegp();
 
 }
diff --git a/similar/main/gamemine.cpp b/similar/main/gamemine.cpp
index df6305652..e3eb09176 100644
--- a/similar/main/gamemine.cpp
+++ b/similar/main/gamemine.cpp
@@ -617,7 +617,7 @@ int load_mine_data(PHYSFS_file *LoadFile)
 
 			Error( "Error seeking to segment_offset in gamemine.c" );
 
-		Highest_segment_index = mine_fileinfo.segment_howmany-1;
+		Segments.set_count(mine_fileinfo.segment_howmany);
 
 		for (segnum_t ii = 0; ii < mine_fileinfo.segment_howmany; ++ii)
 		{
@@ -772,16 +772,16 @@ int load_mine_data(PHYSFS_file *LoadFile)
 	Num_vertices = mine_fileinfo.vertex_howmany;
 	Num_segments = mine_fileinfo.segment_howmany;
 	Highest_vertex_index = Num_vertices-1;
-	Highest_segment_index = Num_segments-1;
+	Segments.set_count(Num_segments);
 
 	reset_objects(1);		//one object, the player
 
 	#ifdef EDITOR
 	Highest_vertex_index = MAX_SEGMENT_VERTICES-1;
-	Highest_segment_index = MAX_SEGMENTS-1;
+	Segments.set_count(MAX_SEGMENTS);
 	set_vertex_counts();
 	Highest_vertex_index = Num_vertices-1;
-	Highest_segment_index = Num_segments-1;
+	Segments.set_count(Num_segments);
 
 	warn_if_concave_segments();
 	#endif
@@ -1012,7 +1012,7 @@ int load_mine_data_compiled(PHYSFS_file *LoadFile)
 	}
 
 	Highest_vertex_index = Num_vertices-1;
-	Highest_segment_index = Num_segments-1;
+	Segments.set_count(Num_segments);
 
 	validate_segment_all();			// Fill in side type and normals.
 
diff --git a/similar/main/gamesave.cpp b/similar/main/gamesave.cpp
index 42a5abfb1..36a88e786 100644
--- a/similar/main/gamesave.cpp
+++ b/similar/main/gamesave.cpp
@@ -1464,7 +1464,7 @@ int create_new_mine(void)
 	Num_vertices = 0;		// Number of vertices in global array.
 	Highest_vertex_index = 0;
 	Num_segments = 0;		// Number of segments in global array, will get increased in med_create_segment
-	Highest_segment_index = 0;
+	Segments.set_count(1);
 	Cursegp = segptridx(segment_first);	// Say current segment is the only segment.
 	Curside = WBACK;		// The active side is the back side
 	Markedsegp = segment_none;		// Say there is no marked segment.