diff --git a/imgui_draw.cpp b/imgui_draw.cpp
index ea822146..efcdacd7 100644
--- a/imgui_draw.cpp
+++ b/imgui_draw.cpp
@@ -1774,19 +1774,34 @@ bool    ImFontAtlasBuildWithStbTruetype(ImFontAtlas* atlas)
             buf_packedchars_n += range.num_chars;
         }
 
-        // Pack
+        // Gather the sizes of all rectangle we need
         tmp.Rects = buf_rects + buf_rects_n;
         tmp.RectsCount = font_glyphs_count;
         buf_rects_n += font_glyphs_count;
         stbtt_PackSetOversampling(&spc, cfg.OversampleH, cfg.OversampleV);
         int n = stbtt_PackFontRangesGatherRects(&spc, &tmp.FontInfo, tmp.Ranges, tmp.RangesCount, tmp.Rects);
         IM_ASSERT(n == font_glyphs_count);
+
+        // Detect missing glyphs and replace them with a zero-sized box instead of relying on the default glyphs
+        // This allows us merging overlapping icon fonts more easily.
+        int rect_i = 0;
+        for (int range_i = 0; range_i < tmp.RangesCount; range_i++)
+            for (int char_i = 0; char_i < tmp.Ranges[range_i].num_chars; char_i++, rect_i++)
+                if (stbtt_FindGlyphIndex(&tmp.FontInfo, tmp.Ranges[range_i].first_unicode_codepoint_in_range + char_i) == 0)
+                    tmp.Rects[rect_i].w = tmp.Rects[rect_i].h = 0;
+
+        // Pack
         stbrp_pack_rects((stbrp_context*)spc.pack_info, tmp.Rects, n);
 
         // Extend texture height
+        // Also mark missing glyphs as non-packed so we don't attempt to render into them
         for (int i = 0; i < n; i++)
+        {
+            if (tmp.Rects[i].w == 0 && tmp.Rects[i].h == 0)
+                tmp.Rects[i].was_packed = 0;
             if (tmp.Rects[i].was_packed)
                 atlas->TexHeight = ImMax(atlas->TexHeight, tmp.Rects[i].y + tmp.Rects[i].h);
+        }
     }
     IM_ASSERT(buf_rects_n == total_glyphs_count);
     IM_ASSERT(buf_packedchars_n == total_glyphs_count);
diff --git a/stb_truetype.h b/stb_truetype.h
index 13627d4f..f65deb50 100644
--- a/stb_truetype.h
+++ b/stb_truetype.h
@@ -1,6 +1,3 @@
-// [ImGui] this is a slightly modified version of stb_truetype.h 1.19. Those changes would need to be pushed into nothings/stb
-// [ImGui] - skip missing glyphs instead of allocating and rendering a default glyph (stb #607, imgui #1703, imgui #1671)
-
 // stb_truetype.h - v1.19 - public domain
 // authored from 2009-2016 by Sean Barrett / RAD Game Tools
 //
@@ -3971,17 +3968,13 @@ STBTT_DEF int stbtt_PackFontRangesGatherRects(stbtt_pack_context *spc, const stb
          int x0,y0,x1,y1;
          int codepoint = ranges[i].array_of_unicode_codepoints == NULL ? ranges[i].first_unicode_codepoint_in_range + j : ranges[i].array_of_unicode_codepoints[j];
          int glyph = stbtt_FindGlyphIndex(info, codepoint);
-         if (glyph != 0) {
-            stbtt_GetGlyphBitmapBoxSubpixel(info,glyph,
-                                            scale * spc->h_oversample,
-                                            scale * spc->v_oversample,
-                                            0,0,
-                                            &x0,&y0,&x1,&y1);
-            rects[k].w = (stbrp_coord) (x1-x0 + spc->padding + spc->h_oversample-1);
-            rects[k].h = (stbrp_coord) (y1-y0 + spc->padding + spc->v_oversample-1);
-         } else {
-            rects[k].w = rects[k].h = 0;
-         }
+         stbtt_GetGlyphBitmapBoxSubpixel(info,glyph,
+                                         scale * spc->h_oversample,
+                                         scale * spc->v_oversample,
+                                         0,0,
+                                         &x0,&y0,&x1,&y1);
+         rects[k].w = (stbrp_coord) (x1-x0 + spc->padding + spc->h_oversample-1);
+         rects[k].h = (stbrp_coord) (y1-y0 + spc->padding + spc->v_oversample-1);
          ++k;
       }
    }
@@ -4034,7 +4027,7 @@ STBTT_DEF int stbtt_PackFontRangesRenderIntoRects(stbtt_pack_context *spc, const
       sub_y = stbtt__oversample_shift(spc->v_oversample);
       for (j=0; j < ranges[i].num_chars; ++j) {
          stbrp_rect *r = &rects[k];
-         if (r->was_packed && r->w != 0 && r->h != 0) {
+         if (r->was_packed) {
             stbtt_packedchar *bc = &ranges[i].chardata_for_range[j];
             int advance, lsb, x0,y0,x1,y1;
             int codepoint = ranges[i].array_of_unicode_codepoints == NULL ? ranges[i].first_unicode_codepoint_in_range + j : ranges[i].array_of_unicode_codepoints[j];