diff --git a/.gitignore b/.gitignore
index 3b29812..a1d4620 100755
--- a/.gitignore
+++ b/.gitignore
@@ -7,3 +7,12 @@ DerivedData/
 .swiftpm/config/registries.json
 .swiftpm/xcode/package.xcworkspace/contents.xcworkspacedata
 .netrc
+
+.idea
+*__gen.go
+*__ignore.go
+*.swp
+*.swo
+~i_*
+ig_*
+zzzig_*
diff --git a/Sources/SwiftMath/MathRender/MTMathListBuilder.swift b/Sources/SwiftMath/MathRender/MTMathListBuilder.swift
index 26e713d..707d64b 100755
--- a/Sources/SwiftMath/MathRender/MTMathListBuilder.swift
+++ b/Sources/SwiftMath/MathRender/MTMathListBuilder.swift
@@ -629,7 +629,7 @@ public struct MTMathListBuilder {
         var mutable = ""
         while self.hasCharacters {
             let ch = self.getNextCharacter()
-            if ch == "#" || (ch >= "A" && ch <= "F") || (ch >= "a" && ch <= "f") || (ch >= "0" && ch <= "9") {
+            if ch == "#" || (ch >= "A" && ch <= "Z") || (ch >= "a" && ch <= "z") || (ch >= "0" && ch <= "9") {
                 mutable.append(ch)  // appendString:[NSString stringWithCharacters:&ch length:1]];
             } else {
                 // we went too far