diff --git a/windows/src/developer/TIKE/main/UframeTextEditor.pas b/windows/src/developer/TIKE/main/UframeTextEditor.pas
index 4c51373740..d1b1868e05 100644
--- a/windows/src/developer/TIKE/main/UframeTextEditor.pas
+++ b/windows/src/developer/TIKE/main/UframeTextEditor.pas
@@ -59,7 +59,7 @@ uses
   Dialogs, Menus, ImgList,
   MenuImgList, ExtCtrls,
 
-{$IFDEF USE_PLUSMEMO}
+{IFDEF USE_PLUSMEMO}
   SyntaxHighlight,
   PlusMemo,
   PlusGutter,
@@ -67,7 +67,7 @@ uses
   HtmlHighlight,
   pmprint,
   PMSupport,
-{$ENDIF}
+{ENDIF}
 
   TextFileFormat, UfrmTike,
   System.ImageList, KeymanDeveloperMemo,
@@ -925,7 +925,9 @@ begin
     if ch = '' then Exit;
 
     if Uni_IsSurrogate2(ch[1]) then
-      ch := memo.GetTextPart(memo.SelStart-2, memo.SelStart);
+      ch := memo.GetTextPart(memo.SelStart-2, memo.SelStart)
+    else if Uni_IsSurrogate1(ch[1]) then
+      ch := memo.GetTextPart(memo.SelStart-1, memo.SelStart+1);
 
     token := FormatUnicode(ch);
   end;
diff --git a/windows/src/global/delphi/general/CleartypeDrawCharacter.pas b/windows/src/global/delphi/general/CleartypeDrawCharacter.pas
index a126c552d7..1e842334b3 100644
--- a/windows/src/global/delphi/general/CleartypeDrawCharacter.pas
+++ b/windows/src/global/delphi/general/CleartypeDrawCharacter.pas
@@ -325,7 +325,12 @@ procedure TClearTypeDrawCharacter.SelectFallbackFont(Handle: THandle; const Text
 var
   uc: DWord;
 begin
-  uc := Char.ConvertToUtf32(Text, 0);  // I3310
+  try
+    uc := Char.ConvertToUtf32(Text, 0);  // I3310
+  except
+    on E:EArgumentOutOfRangeException do
+      uc := $FFFD;  // Not a character, invalid Unicode
+  end;
   if uc < $10000 then      SelectFont(Handle, ctfCode2000)
   else if uc < $20000 then SelectFont(Handle, ctfCode2001)
   else if uc < $30000 then SelectFont(Handle, ctfCode2002)