diff --git a/imgui.h b/imgui.h
index 57e58b904..f94423931 100644
--- a/imgui.h
+++ b/imgui.h
@@ -1357,7 +1357,7 @@ struct ImFont
     ImVec2                      DisplayOffset;      // = (0.f,1.f)  // Offset font rendering by xx pixels
     ImVector<Glyph>             Glyphs;             //              // All glyphs.
     ImVector<float>             IndexXAdvance;      //              // Sparse. Glyphs->XAdvance in a directly indexable way (more cache-friendly, for CalcTextSize functions which are often bottleneck in large UI).
-    ImVector<short>             IndexLookup;        //              // Sparse. Index glyphs by Unicode code-point.
+    ImVector<unsigned short>    IndexLookup;        //              // Sparse. Index glyphs by Unicode code-point.
     const Glyph*                FallbackGlyph;      // == FindGlyph(FontFallbackChar)
     float                       FallbackXAdvance;   // == FallbackGlyph->XAdvance
     ImWchar                     FallbackChar;       // = '?'        // Replacement glyph if one isn't found. Only set via SetFallbackChar()
diff --git a/imgui_draw.cpp b/imgui_draw.cpp
index 037670960..5f4854810 100644
--- a/imgui_draw.cpp
+++ b/imgui_draw.cpp
@@ -1695,7 +1695,7 @@ void ImFont::BuildLookupTable()
     for (int i = 0; i != Glyphs.Size; i++)
         max_codepoint = ImMax(max_codepoint, (int)Glyphs[i].Codepoint);
 
-    IM_ASSERT(Glyphs.Size < 32*1024);
+    IM_ASSERT(Glyphs.Size < 0xFFFF); // -1 is reserved
     IndexXAdvance.clear();
     IndexLookup.clear();
     GrowIndex(max_codepoint + 1);
@@ -1703,7 +1703,7 @@ void ImFont::BuildLookupTable()
     {
         int codepoint = (int)Glyphs[i].Codepoint;
         IndexXAdvance[codepoint] = Glyphs[i].XAdvance;
-        IndexLookup[codepoint] = (short)i;
+        IndexLookup[codepoint] = (unsigned short)i;
     }
 
     // Create a glyph to handle TAB
@@ -1717,7 +1717,7 @@ void ImFont::BuildLookupTable()
         tab_glyph.Codepoint = '\t';
         tab_glyph.XAdvance *= 4;
         IndexXAdvance[(int)tab_glyph.Codepoint] = (float)tab_glyph.XAdvance;
-        IndexLookup[(int)tab_glyph.Codepoint] = (short)(Glyphs.Size-1);
+        IndexLookup[(int)tab_glyph.Codepoint] = (unsigned short)(Glyphs.Size-1);
     }
 
     FallbackGlyph = NULL;
@@ -1745,7 +1745,7 @@ void ImFont::GrowIndex(int new_size)
     for (int i = old_size; i < new_size; i++)
     {
         IndexXAdvance[i] = -1.0f;
-        IndexLookup[i] = (short)-1;
+        IndexLookup[i] = (unsigned short)-1;
     }
 }
 
@@ -1754,13 +1754,13 @@ void ImFont::AddRemapChar(ImWchar dst, ImWchar src, bool overwrite_dst)
     IM_ASSERT(IndexLookup.Size > 0);    // Currently this can only be called AFTER the font has been built, aka after calling ImFontAtlas::GetTexDataAs*() function.
     int index_size = IndexLookup.Size;
 
-    if (dst < index_size && IndexLookup.Data[dst] == -1 && !overwrite_dst) // 'dst' already exists
+    if (dst < index_size && IndexLookup.Data[dst] == (unsigned short)-1 && !overwrite_dst) // 'dst' already exists
         return;
     if (src >= index_size && dst >= index_size) // both 'dst' and 'src' don't exist -> no-op
         return;
 
     GrowIndex(dst + 1);
-    IndexLookup[dst] = (src < index_size) ? IndexLookup.Data[src] : -1;
+    IndexLookup[dst] = (src < index_size) ? IndexLookup.Data[src] : (unsigned short)-1;
     IndexXAdvance[dst] = (src < index_size) ? IndexXAdvance.Data[src] : 1.0f;
 }
 
@@ -1768,8 +1768,8 @@ const ImFont::Glyph* ImFont::FindGlyph(unsigned short c) const
 {
     if (c < IndexLookup.Size)
     {
-        const short i = IndexLookup[c];
-        if (i != -1)
+        const unsigned short i = IndexLookup[c];
+        if (i != (unsigned short)-1)
             return &Glyphs.Data[i];
     }
     return FallbackGlyph;