diff --git a/src/kernel/tqfontengine_x11.cpp b/src/kernel/tqfontengine_x11.cpp
index 6363aac9..8002c42d 100644
--- a/src/kernel/tqfontengine_x11.cpp
+++ b/src/kernel/tqfontengine_x11.cpp
@@ -2264,6 +2264,8 @@ struct OTScripts {
     int flags;
 };
 
+// Refer to https://learn.microsoft.com/en-us/typography/opentype/spec/scripttags
+// for OpenType language tags definition
 static const OTScripts ot_scripts [] = {
 // 	// European Alphabetic Scripts
 // 	Latin,
@@ -2351,6 +2353,7 @@ static const OTScripts ot_scripts [] = {
     { FT_MAKE_TAG( 'c', 'a', 'n', 's' ), 0 },
 // 	Mongolian,
     { FT_MAKE_TAG( 'm', 'o', 'n', 'g' ), 0 },
+
 // 	// Symbols
 // 	CurrencySymbols,
     { FT_MAKE_TAG( 'D', 'F', 'L', 'T' ), 0 },
@@ -2370,13 +2373,26 @@ static const OTScripts ot_scripts [] = {
     { FT_MAKE_TAG( 'D', 'F', 'L', 'T' ), 0 },
 // 	Braille,
     { FT_MAKE_TAG( 'b', 'r', 'a', 'i' ), 0 },
-//                Unicode, should be used
-    { FT_MAKE_TAG( 'D', 'F', 'L', 'T' ), 0 }
-    // ### where are these?
-// 	{ FT_MAKE_TAG( 'b', 'y', 'z', 'm' ), 0 },
-//     { FT_MAKE_TAG( 'D', 'F', 'L', 'T' ), 0 },
-    // ### Hangul Jamo
-//     { FT_MAKE_TAG( 'j', 'a', 'm', 'o' ), 0 },
+
+// 	Unicode
+    { FT_MAKE_TAG( 'D', 'F', 'L', 'T' ), 0 },
+
+// 	Tagalog,
+    { FT_MAKE_TAG( 't', 'g', 'l', 'g' ), 0 },
+// 	Hanunoo,
+    { FT_MAKE_TAG( 'h', 'a', 'n', 'o' ), 0 },
+// 	Buhid,
+    { FT_MAKE_TAG( 'b', 'u', 'h', 'd' ), 0 },
+// 	Tagbanwa,
+    { FT_MAKE_TAG( 't', 'a', 'g', 'b' ), 0 },
+
+// 	KatakanaHalfWidth, -- can't find it, use Katakana code
+    { FT_MAKE_TAG( 'k', 'a', 'n', 'a' ), 0 },
+
+// 	Limbu,
+    { FT_MAKE_TAG( 'l', 'i', 'm', 'b' ), 0 },
+// 	TaiLe,
+    { FT_MAKE_TAG( 't', 'a', 'l', 'e' ), 0 }
 };
 
 TQOpenType::TQOpenType(TQFontEngineXft *fe)
@@ -2435,7 +2451,10 @@ TQOpenType::~TQOpenType()
 
 bool TQOpenType::checkScript(unsigned int script)
 {
-    assert(script < TQFont::NScripts);
+    if (script >= TQFont::NScripts || script >= sizeof(ot_scripts) / sizeof(OTScripts))
+    {
+      return false;
+    }
 
     uint tag = ot_scripts[script].tag;
     int requirements = ot_scripts[script].flags;
@@ -2477,7 +2496,11 @@ void TQOpenType::selectScript(unsigned int script, const Features *features)
     if (current_script == script)
         return;
 
-    assert(script < TQFont::NScripts);
+    if (script >= TQFont::NScripts || script >= sizeof(ot_scripts) / sizeof(OTScripts))
+    {
+        return;
+    }
+
     // find script in our list of supported scripts.
     uint tag = ot_scripts[script].tag;