diff --git a/src/UglyToad.PdfPig/Fonts/TrueType/Parser/TableRegister.cs b/src/UglyToad.PdfPig/Fonts/TrueType/Parser/TableRegister.cs
index d01f1531..dc80e7ee 100644
--- a/src/UglyToad.PdfPig/Fonts/TrueType/Parser/TableRegister.cs
+++ b/src/UglyToad.PdfPig/Fonts/TrueType/Parser/TableRegister.cs
@@ -18,7 +18,6 @@
         /// <summary>
         /// This table contains the data that defines the appearance of the glyphs in the font.
         /// </summary>
-        [NotNull]
         public GlyphDataTable GlyphTable { get; }
 
         /// <summary>
@@ -36,7 +35,6 @@
         /// <summary>
         /// This table stores the offsets to the locations of the glyphs (relative to the glyph table).
         /// </summary>
-        [NotNull]
         public IndexToLocationTable IndexToLocationTable { get; }
 
         /// <summary>
@@ -73,10 +71,10 @@
             }
 
             HeaderTable = builder.HeaderTable ?? throw new ArgumentException("The builder did not contain the header table");
-            GlyphTable = builder.GlyphDataTable ?? throw new ArgumentException("The builder did not contain the glyph data table.");
+            GlyphTable = builder.GlyphDataTable;
             HorizontalHeaderTable = builder.HorizontalHeaderTable ?? throw new ArgumentException("The builder did not contain the horizontal header table.");
             HorizontalMetricsTable = builder.HorizontalMetricsTable;
-            IndexToLocationTable = builder.IndexToLocationTable ?? throw new ArgumentException("The builder did not contain the index to location table.");
+            IndexToLocationTable = builder.IndexToLocationTable;
             MaximumProfileTable = builder.MaximumProfileTable ?? throw new ArgumentException("The builder did not contain the maximum profile table.");
             NameTable = builder.NameTable;
             PostScriptTable = builder.PostScriptTable;
diff --git a/src/UglyToad.PdfPig/Fonts/TrueType/Parser/TrueTypeFontParser.cs b/src/UglyToad.PdfPig/Fonts/TrueType/Parser/TrueTypeFontParser.cs
index 7b982c3f..ca85b404 100644
--- a/src/UglyToad.PdfPig/Fonts/TrueType/Parser/TrueTypeFontParser.cs
+++ b/src/UglyToad.PdfPig/Fonts/TrueType/Parser/TrueTypeFontParser.cs
@@ -20,7 +20,7 @@
             int rangeShift = data.ReadUnsignedShort();
             // ReSharper restore UnusedVariable
 
-            var tables = new Dictionary<string, TrueTypeHeaderTable>();
+            var tables = new Dictionary<string, TrueTypeHeaderTable>(StringComparer.OrdinalIgnoreCase);
 
             for (var i = 0; i < numberOfTables; i++)
             {
@@ -46,7 +46,7 @@
             var length = data.ReadUnsignedInt();
 
             // skip tables with zero length (except glyf)
-            if (length == 0 && !string.Equals(tag, TrueTypeHeaderTable.Glyf))
+            if (length == 0 && !string.Equals(tag, TrueTypeHeaderTable.Glyf, StringComparison.OrdinalIgnoreCase))
             {
                 return null;
             }
diff --git a/src/UglyToad.PdfPig/Fonts/TrueType/TrueTypeFontProgram.cs b/src/UglyToad.PdfPig/Fonts/TrueType/TrueTypeFontProgram.cs
index 5298a8ad..1dab1129 100644
--- a/src/UglyToad.PdfPig/Fonts/TrueType/TrueTypeFontProgram.cs
+++ b/src/UglyToad.PdfPig/Fonts/TrueType/TrueTypeFontProgram.cs
@@ -68,7 +68,8 @@
         {
             boundingBox = default(PdfRectangle);
 
-            if (!TryGetGlyphIndex(characterIdentifier, characterCodeToGlyphId, out var index))
+            if (!TryGetGlyphIndex(characterIdentifier, characterCodeToGlyphId, out var index)
+                || TableRegister.GlyphTable == null)
             {
                 return false;
             }
@@ -112,6 +113,13 @@
 
         private bool TryGetBoundingAdvancedWidthByIndex(int index, out decimal width)
         {
+            width = 0;
+
+            if (TableRegister.HorizontalMetricsTable == null)
+            {
+                return false;
+            }
+
             width = TableRegister.HorizontalMetricsTable.GetAdvanceWidth(index);
 
             return true;