diff --git a/lslopt/lslbasefuncs.py b/lslopt/lslbasefuncs.py
index 1ba6375..683b15d 100644
--- a/lslopt/lslbasefuncs.py
+++ b/lslopt/lslbasefuncs.py
@@ -1153,50 +1153,10 @@ def llCeil(f):
 
 def llChar(code):
     code = fi(code)
-    # The result is consistent with a conversion of the codepoint to
-    # UTF-8-1993, then using InternalUTF8toString on the result.
-    # A thorough test shows that llChar(n) equals llUnescapeURL(utf8_1993)
-    # up to codepoint 0x13FFFF. Furthermore llChar(0x200000) returns "?????",
-    # and llChar(0x7FFFFFFF) returns "??????", which are also consistent with
-    # that. LSO also returns UTF-8-1993 for codepoints > 0x10FFFF. So, the
-    # internal implementation is likely to form a UTF8-1993 string from the
-    # codepoint and then convert that to string, like this:
-#    if code < 0:
-#       return u'?'
-#    if code < 0x80:
-#        s = (code,)
-#    elif code < 0x800:
-#        s = (0xC0+(code >> 6), 0x80+(code&0x3F))
-#    elif code < 0x10000:
-#        s = (0xE0+(code >> 12), 0x80+((code >> 6)&0x3F), 0x80+(code&0x3F))
-#    elif code < 0x200000:
-#        s = (0xF0+(code >> 18), 0x80+((code >> 12)&0x3F),
-#            0x80+((code >> 6)&0x3F), 0x80+(code&0x3F))
-#    elif code < 0x4000000:
-#        s = (0xF8+(code >> 24),
-#            0x80+((code >> 18)&0x3F), 0x80+((code >> 12)&0x3F),
-#            0x80+((code >> 6)&0x3F), 0x80+(code&0x3F))
-#    else:
-#        s = (0xFC+(code >> 30), 0x80+((code >> 24)&0x3F),
-#            0x80+((code >> 18)&0x3F), 0x80+((code >> 12)&0x3F),
-#            0x80+((code >> 6)&0x3F), 0x80+(code&0x3F))
-#    return zstr(InternalUTF8toString(bytearray(s)))
 
-    # Here's an alternative, simpler implementation that only works for Mono:
-    if lslcommon.LSO:
-        raise ELSLCantCompute
-    if code <= 0 or code > 0x10FFFF:
-        if code == 0:
-            return u''
-        if code < 0:
-            return u'?'
-        if code >= 0x4000000:
-            return u'??????'
-        if code >= 0x200000:
-            return u'?????'
-        return u'????'
-    if (0xD800 <= code <= 0xDFFF) or code == 0xFFFE:
-        return u'???'
+    if (not 1 <= code <= 0x10FFFF or 0xD800 <= code <= 0xDFFF
+            or code == 0xFFFE or code == 0xFFFF):
+        return u'' if code == 0 else u'\uFFFD'
     return unichr(code)
 
 def llCos(f):
diff --git a/unit_tests/expr.suite/llord-char-hash.lsl b/unit_tests/expr.suite/llord-char-hash.lsl
index 1a8a3dc..85cf564 100644
--- a/unit_tests/expr.suite/llord-char-hash.lsl
+++ b/unit_tests/expr.suite/llord-char-hash.lsl
@@ -5,12 +5,15 @@
 , llOrd(".", 1)
 , llOrd(".", 2)
 , llOrd("ð", 0)
+, llOrd("𝄞𝐀", -1)
 , llOrd("𝄞𝐀", 0)
 , llOrd("𝄞𝐀", 1)
 , llOrd("𝄞𝐀", 2)
 , llOrd("𝄞𝐀", 3)
+, llOrd("𝄞𝐀", 4)
 , llOrd(JSON_TRUE, 0)
 , llOrd(llUnescapeURL("%EF%BF%BF"), 0)
+, llEscapeURL(llChar(-123456789))
 , llEscapeURL(llChar(-123))
 , llEscapeURL(llChar(-1))
 , llEscapeURL(llChar(0))
diff --git a/unit_tests/expr.suite/llord-char-hash.out b/unit_tests/expr.suite/llord-char-hash.out
index c33b750..117d99f 100644
--- a/unit_tests/expr.suite/llord-char-hash.out
+++ b/unit_tests/expr.suite/llord-char-hash.out
@@ -5,30 +5,33 @@
 , 0
 , 0
 , 240
+, 119808
 , 119070
 , 119808
 , 0
 , 0
+, 0
 , 64982
 , 65535
-, "%3F"
-, "%3F"
+, "%EF%BF%BD"
+, "%EF%BF%BD"
+, "%EF%BF%BD"
 , ""
 , "%01"
 , "%C2%A9"
 , "%C5%8D"
 , "%E2%80%90"
-, "%3F%3F%3F"
-, "%3F%3F%3F"
-, "%3F%3F%3F"
-, "%EF%BF%BF"
+, "%EF%BF%BD"
+, "%EF%BF%BD"
+, "%EF%BF%BD"
+, "%EF%BF%BD"
 , "%F0%9F%98%80"
 , "%F4%8F%BF%BF"
-, "%3F%3F%3F%3F"
-, "%3F%3F%3F%3F%3F"
-, "%3F%3F%3F%3F%3F%3F"
-, "%3F%3F%3F%3F%3F%3F"
-, "%3F"
+, "%EF%BF%BD"
+, "%EF%BF%BD"
+, "%EF%BF%BD"
+, "%EF%BF%BD"
+, "%EF%BF%BD"
 , 1203819346
 , 0
 , 1172851538
diff --git a/unit_tests/expr.suite/string-funcs.lsl b/unit_tests/expr.suite/string-funcs.lsl
index 5662a17..156d2ab 100644
--- a/unit_tests/expr.suite/string-funcs.lsl
+++ b/unit_tests/expr.suite/string-funcs.lsl
@@ -182,9 +182,14 @@
 , llGetSubString("abcd",  9,  3)
 , llGetSubString("abcd",  9,  4)
 , llGetSubString("abcd",  9,  5)
+, llGetSubString("😀bcd",  0,  0)
+, llGetSubString("😀bcd",  1,  1)
+, llGetSubString("😀bcd",  2,  2)
+, llGetSubString("😀bcd",  3,  3)
+, llGetSubString("😀bcd",  4,  4)
 , llGetSubString("", 0, -1)
 , llStringLength("")
-, llStringLength("÷½¬⅛⅜⅝⅞±°z")
+, llStringLength("÷½¬⅛⅜⅝⅞😀±°z")
 , llSubStringIndex("x", "blah")
 , llSubStringIndex("", "")
 , llSubStringIndex("", "x")
diff --git a/unit_tests/expr.suite/string-funcs.out b/unit_tests/expr.suite/string-funcs.out
index 1d19099..09466a3 100644
--- a/unit_tests/expr.suite/string-funcs.out
+++ b/unit_tests/expr.suite/string-funcs.out
@@ -182,9 +182,14 @@
 , "abcd"
 , "abcd"
 , "abcd"
+, "😀"
+, "b"
+, "c"
+, "d"
+, ""
 , ""
 , 0
-, 10
+, 11
 , -1
 , 0
 , -1