diff --git a/doc/fixes37.0 b/doc/fixes37.0
index 2921d7b88..af0bdfaaa 100644
--- a/doc/fixes37.0
+++ b/doc/fixes37.0
@@ -13,6 +13,8 @@ improvements to pronoun usage when hallucinating
 message "your knapsack can't accomodate any more items" when picking stuff up
 	or removing such from container was inaccurate if there was some gold
 	pending; vary the message rather than add more convoluted pickup code
+function calls made from mapglyph based on dungeon level are now called once
+	per level
 
 
 Fixes to Pre-3.7.0 Problems that Were Exposed Via git Repository
diff --git a/include/decl.h b/include/decl.h
index ce0ecabe8..d6100e241 100644
--- a/include/decl.h
+++ b/include/decl.h
@@ -1260,6 +1260,9 @@ struct instance_globals {
     char lua_ver[LUA_VER_BUFSIZ];
     char lua_copyright[LUA_COPYRIGHT_BUFSIZ];
 
+    /* per-level glyph mapping flags */
+    long glyphmap_perlevel_flags;
+
     unsigned long magic; /* validate that structure layout is preserved */
 };
 
diff --git a/src/decl.c b/src/decl.c
index a0c3a9d4a..8ae9aa6c7 100644
--- a/src/decl.c
+++ b/src/decl.c
@@ -695,6 +695,9 @@ const struct instance_globals g_init = {
     DUMMY,   /* lua_ver[LUA_VER_BUFSIZ] */
     DUMMY,   /* lua_copyright[LUA_COPYRIGHT_BUFSIZ] */
 
+    /* per-level glyph mapping flags */
+    0L,     /* glyphmap_perlevel_flags */
+
     IVMAGIC  /* used to validate that structure layout has been preserved */
 };
 
diff --git a/src/do.c b/src/do.c
index 9cf5669ad..9b5cbd965 100644
--- a/src/do.c
+++ b/src/do.c
@@ -1578,6 +1578,7 @@ boolean at_stairs, falling, portal;
 
     /* Reset the screen. */
     vision_reset(); /* reset the blockages */
+    g.glyphmap_perlevel_flags = 0L; /* force per-level mapglyph() changes */
     docrt();        /* does a full vision recalc */
     flush_screen(-1);
 
diff --git a/src/mapglyph.c b/src/mapglyph.c
index bc7e4f727..7a28091d9 100644
--- a/src/mapglyph.c
+++ b/src/mapglyph.c
@@ -9,9 +9,11 @@
 #include "color.h"
 #define HI_DOMESTIC CLR_WHITE /* monst.c */
 
+#if 0
 #if !defined(TTY_GRAPHICS)
 #define has_color(n) TRUE
 #endif
+#endif
 
 #ifdef TEXTCOLOR
 static const int explcolors[] = {
@@ -57,6 +59,10 @@ static const int explcolors[] = {
 #define is_objpile(x,y) (!Hallucination && g.level.objects[(x)][(y)] \
                          && g.level.objects[(x)][(y)]->nexthere)
 
+#define GMAP_SET                 0x00000001
+#define GMAP_ROGUELEVEL          0x00000002
+#define GMAP_ALTARCOLOR          0x00000004
+
 /*ARGSUSED*/
 int
 mapglyph(glyph, ochar, ocolor, ospecial, x, y, mgflags)
@@ -75,6 +81,21 @@ unsigned mgflags;
             has_rogue_color = (has_rogue_ibm_graphics
                                && g.symset[g.currentgraphics].nocolor == 0);
 
+    if (!g.glyphmap_perlevel_flags) {
+        /*
+         *    GMAP_SET                0x00000001
+         *    GMAP_ROGUELEVEL         0x00000002
+         *    GMAP_ALTARCOLOR         0x00000004
+         */
+        g.glyphmap_perlevel_flags |= GMAP_SET;
+
+        if (Is_rogue_level(&u.uz)) {
+            g.glyphmap_perlevel_flags |= GMAP_ROGUELEVEL;
+        } else if ((Is_astralevel(&u.uz) || Is_sanctum(&u.uz))) {
+            g.glyphmap_perlevel_flags |= GMAP_ALTARCOLOR;
+        }
+    }
+
     /*
      *  Map the glyph back to a character and color.
      *
@@ -142,7 +163,7 @@ unsigned mgflags;
                           == g.showsyms[S_water + SYM_OFF_P])) {
             special |= MG_BW_LAVA;
         } else if (offset == S_altar && iflags.use_color) {
-            if ((Is_astralevel(&u.uz) || Is_sanctum(&u.uz))
+            if ((g.glyphmap_perlevel_flags & GMAP_ALTARCOLOR)
                 && (levl[x][y].altarmask & AM_SHRINE)) {
                 /* high altar */
                 color = CLR_BRIGHT_MAGENTA;
@@ -273,14 +294,16 @@ unsigned mgflags;
 
         if ((special & MG_PET) != 0) {
             ovidx = SYM_PET_OVERRIDE + SYM_OFF_X;
-            if (Is_rogue_level(&u.uz) ? g.ov_rogue_syms[ovidx]
-                                      : g.ov_primary_syms[ovidx])
+            if ((g.glyphmap_perlevel_flags & GMAP_ROGUELEVEL)
+                    ? g.ov_rogue_syms[ovidx]
+                    : g.ov_primary_syms[ovidx])
                 idx = ovidx;
         }
         if (is_you) {
             ovidx = SYM_HERO_OVERRIDE + SYM_OFF_X;
-            if (Is_rogue_level(&u.uz) ? g.ov_rogue_syms[ovidx]
-                                      : g.ov_primary_syms[ovidx])
+            if ((g.glyphmap_perlevel_flags & GMAP_ROGUELEVEL)
+                    ? g.ov_rogue_syms[ovidx]
+                    : g.ov_primary_syms[ovidx])
                 idx = ovidx;
         }
     }
@@ -288,7 +311,8 @@ unsigned mgflags;
     ch = g.showsyms[idx];
 #ifdef TEXTCOLOR
     /* Turn off color if no color defined, or rogue level w/o PC graphics. */
-    if (!has_color(color) || (Is_rogue_level(&u.uz) && !has_rogue_color))
+    if (!has_color(color) ||
+            ((g.glyphmap_perlevel_flags & GMAP_ROGUELEVEL) && !has_rogue_color))
 #endif
         color = NO_COLOR;
     *ochar = (int) ch;