diff --git a/src/UglyToad.PdfPig.Fonts/GlyphList.cs b/src/UglyToad.PdfPig.Fonts/GlyphList.cs
index aa264b05..b9ce8c53 100644
--- a/src/UglyToad.PdfPig.Fonts/GlyphList.cs
+++ b/src/UglyToad.PdfPig.Fonts/GlyphList.cs
@@ -22,20 +22,13 @@
 
         private readonly Dictionary<string, string> oddNameToUnicodeCache = new Dictionary<string, string>();
 
-        private static readonly Lazy<GlyphList> LazyAdobeGlyphList = new Lazy<GlyphList>(() => GlyphListFactory.Get("glyphlist"));
+        private static readonly Lazy<GlyphList> LazyAdobeGlyphList = new Lazy<GlyphList>(() => GlyphListFactory.Get("glyphlist", "additional"));
 
         /// <summary>
-        /// The Adobe Glyph List.
+        /// The Adobe Glyph List (includes an extension to the Adobe Glyph List.).
         /// </summary>
         public static GlyphList AdobeGlyphList => LazyAdobeGlyphList.Value;
 
-        private static readonly Lazy<GlyphList> LazyAdditionalGlyphList = new Lazy<GlyphList>(() => GlyphListFactory.Get("additional"));
-
-        /// <summary>
-        /// An extension to the Adobe Glyph List.
-        /// </summary>
-        public static GlyphList AdditionalGlyphList => LazyAdditionalGlyphList.Value;
-
         private static readonly Lazy<GlyphList> LazyZapfDingbatsGlyphList = new Lazy<GlyphList>(() => GlyphListFactory.Get("zapfdingbats"));
         
         /// <summary>
@@ -103,7 +96,7 @@
                 return result;
             }
 
-            string unicode;
+            string? unicode;
             // 1. Drop all the characters from the glyph name starting with the first occurrence of a period (U+002E FULL STOP), if any.
             if (name.IndexOf('.') > 0)
             {
diff --git a/src/UglyToad.PdfPig.Fonts/GlyphListFactory.cs b/src/UglyToad.PdfPig.Fonts/GlyphListFactory.cs
index 39a6cedf..667f5de9 100644
--- a/src/UglyToad.PdfPig.Fonts/GlyphListFactory.cs
+++ b/src/UglyToad.PdfPig.Fonts/GlyphListFactory.cs
@@ -4,49 +4,56 @@
     using System.Collections.Generic;
     using System.Globalization;
     using System.IO;
+    using System.Linq;
     using Util;
 
-    internal class GlyphListFactory
+    internal static class GlyphListFactory
     {
-        public static GlyphList Get(string listName)
+#if NET
+        private const char Semicolon = ';';
+#else
+        private static readonly char[] Semicolon = [';'];
+#endif
+
+        public static GlyphList Get(params string[] listNames)
         {
-            using (var resource =
-                typeof(GlyphListFactory).Assembly.GetManifestResourceStream(
-                    $"UglyToad.PdfPig.Fonts.Resources.GlyphList.{listName}"))
+            var result = new Dictionary<string, string>(listNames.Any(n => string.Equals("glyphlist", n, StringComparison.OrdinalIgnoreCase)) ? 4300 : 0);
+
+            foreach (var listName in listNames)
             {
-                if (resource == null)
+                using (var resource =
+                       typeof(GlyphListFactory).Assembly.GetManifestResourceStream(
+                           $"UglyToad.PdfPig.Fonts.Resources.GlyphList.{listName}"))
                 {
-                    throw new ArgumentException($"No embedded glyph list resource was found with the name {listName}.");
-                }
+                    if (resource == null)
+                    {
+                        throw new ArgumentException($"No embedded glyph list resource was found with the name {listName}.");
+                    }
 
-                int? capacity = null;
-                // Prevent too much wasted memory capacity for Adobe GlyphList
-                if (string.Equals("glyphlist", listName, StringComparison.OrdinalIgnoreCase))
-                {
-                    capacity = 4300;
+                    ReadInternal(resource, result);
                 }
-
-                return ReadInternal(resource, capacity);
             }
+
+#if NET
+            result.TrimExcess();
+#endif
+            return new GlyphList(result);
         }
 
         public static GlyphList Read(Stream stream)
         {
-            return ReadInternal(stream);
+            var result = new Dictionary<string, string>();
+            ReadInternal(stream, result);
+            return new GlyphList(result);
         }
 
-        private static readonly char[] Semicolon = [';'];
-
-        private static GlyphList ReadInternal(Stream stream, int? defaultDictionaryCapacity = 0)
+        private static void ReadInternal(Stream stream, Dictionary<string, string> result)
         {
             if (stream == null)
             {
                 throw new ArgumentNullException(nameof(stream));
             }
 
-            var result = defaultDictionaryCapacity.HasValue ? new Dictionary<string, string>(defaultDictionaryCapacity.Value) : [];
-
-
             using (var reader = new StreamReader(stream))
             {
                 while (!reader.EndOfStream)
@@ -62,7 +69,7 @@
                     {
                         continue;
                     }
-
+                    
                     var parts = line.Split(Semicolon, StringSplitOptions.RemoveEmptyEntries);
 
                     if (parts.Length != 2)
@@ -86,11 +93,10 @@
                         value += char.ConvertFromUtf32(code);
                     }
 
+                    System.Diagnostics.Debug.Assert(!result.ContainsKey(key));
                     result[key] = value;
                 }
             }
-
-            return new GlyphList(result);
         }
     }
 }
diff --git a/src/UglyToad.PdfPig.Tests/Integration/AdditionalGlyphListTests.cs b/src/UglyToad.PdfPig.Tests/Integration/AdditionalGlyphListTests.cs
new file mode 100644
index 00000000..002b2167
--- /dev/null
+++ b/src/UglyToad.PdfPig.Tests/Integration/AdditionalGlyphListTests.cs
@@ -0,0 +1,42 @@
+namespace UglyToad.PdfPig.Tests.Integration
+{
+    using System.Linq;
+
+    public class AdditionalGlyphListTests
+    {
+        [Fact]
+        public void Type1FontSimple1()
+        {
+            using (var document = PdfDocument.Open(IntegrationHelpers.GetDocumentPath("2108.11480")))
+            {
+                var page = document.GetPage(2);
+                Assert.Contains("\u22c3", page.Letters.Select(l => l.Value));
+            }
+        }
+
+        [Fact]
+        public void Type1FontSimple2()
+        {
+            using (var document = PdfDocument.Open(IntegrationHelpers.GetDocumentPath("ICML03-081")))
+            {
+                var page = document.GetPage(2);
+                Assert.Contains("\u2211", page.Letters.Select(l => l.Value));
+                Assert.Contains("\u220f", page.Letters.Select(l => l.Value));
+                Assert.Contains("[", page.Letters.Select(l => l.Value));
+                Assert.Contains("]", page.Letters.Select(l => l.Value));
+            }
+        }
+
+        [Fact]
+        public void Type1FontSimple3()
+        {
+            using (var document = PdfDocument.Open(IntegrationHelpers.GetDocumentPath("Math119FakingData")))
+            {
+                var page = document.GetPage(4);
+                Assert.Contains("(", page.Letters.Select(l => l.Value));
+                Assert.Contains(")", page.Letters.Select(l => l.Value));
+                Assert.Contains("\u2211", page.Letters.Select(l => l.Value));
+            }
+        }
+    }
+}
diff --git a/src/UglyToad.PdfPig/PdfFonts/Simple/TrueTypeSimpleFont.cs b/src/UglyToad.PdfPig/PdfFonts/Simple/TrueTypeSimpleFont.cs
index 13e4162d..9418d8a9 100644
--- a/src/UglyToad.PdfPig/PdfFonts/Simple/TrueTypeSimpleFont.cs
+++ b/src/UglyToad.PdfPig/PdfFonts/Simple/TrueTypeSimpleFont.cs
@@ -102,8 +102,7 @@
             // Look up the character name in the Adobe Glyph List or additional Glyph List.
             try
             {
-                value = GlyphList.AdobeGlyphList.NameToUnicode(encodedCharacterName)
-                        ?? GlyphList.AdditionalGlyphList.NameToUnicode(encodedCharacterName);
+                value = GlyphList.AdobeGlyphList.NameToUnicode(encodedCharacterName);
             }
             catch
             {