diff --git a/lib/LaTeXML/Common/Color.pm b/lib/LaTeXML/Common/Color.pm
index db1d8d041e..623101fd30 100644
--- a/lib/LaTeXML/Common/Color.pm
+++ b/lib/LaTeXML/Common/Color.pm
@@ -157,7 +157,7 @@ sub multiply {
 
 __END__
 
-=pod 
+=pod
 
 =head1 NAME
 
@@ -251,4 +251,3 @@ Public domain software, produced as part of work done by the
 United States Government & not subject to copyright in the US.
 
 =cut
-
diff --git a/lib/LaTeXML/Common/Color/rgb.pm b/lib/LaTeXML/Common/Color/rgb.pm
index 71706232cf..ca62d65840 100644
--- a/lib/LaTeXML/Common/Color/rgb.pm
+++ b/lib/LaTeXML/Common/Color/rgb.pm
@@ -51,12 +51,14 @@ sub hsb {
   elsif ($i == 6) { return Phi($r, $g, $b, 1, -1); }
   elsif ($i == 7) { return LaTeXML::Common::Color->new('hsb', 0, 0, $b); } }
 
-my @hex = qw(0 1 2 3 4 5 6 7 8 9 A B C D E F);    # [CONSTANT]
-
 sub hex2 {
-  my ($n) = @_;
-  my $nn = LaTeXML::Common::Number::roundto($n * 255, 0);
-  return $hex[int($nn / 16)] . $hex[$nn % 16]; }
+  my ($n)    = @_;
+  my $nn     = LaTeXML::Common::Number::roundto($n * 255, 0);
+  my $h_full = sprintf("%.2X", $nn);
+  # the precision doesn't quite get enforced on larger values,
+  # so let's try to substring explicitly
+  my $h2 = substr($h_full, 0, 2);
+  return $h2; }
 
 sub toHex {
   my ($self) = @_;
diff --git a/lib/LaTeXML/Package/xcolor.sty.ltxml b/lib/LaTeXML/Package/xcolor.sty.ltxml
index b6cbb0b44d..71ff6bf418 100644
--- a/lib/LaTeXML/Package/xcolor.sty.ltxml
+++ b/lib/LaTeXML/Package/xcolor.sty.ltxml
@@ -278,8 +278,8 @@ sub DecodeColor {
   my $dec_re         = qr/[+-]*(?:\d*\.?\d*)/;
   # <ext_expr>     : <core_model>,<div>:<expr1><dec1>;...;<exprk><deck>
   #                     | <core_model>:<expr1><dec1>;...;<exprk><deck>
-  my $ext_expr_re = qr/($core_model_re)(,($div_re))?:\s*
-                       (($expr_re|$name_re),$dec_re(?:;\s*(?:$expr_re|$name_re),$dec_re)*)/x;
+  my $ext_expr_re = qr/($core_model_re)(,\s*($div_re))?:\s*
+                       (($expr_re|$name_re),\s*$dec_re(?:;\s*(?:$expr_re|$name_re),\s*$dec_re)*)/x;
   # <color_expr>   : <name> | <expr> | <ext_expt>
   my $color_expr_re = qr/$expr_re|$ext_expr_re/;
   my $function_re   = qr/wheel|twheel/;
@@ -305,13 +305,17 @@ sub DecodeColor {
     if (defined $core_model) {    # Extended color expression: combine colors as on a pallete
       $color = Black->convert($core_model);
       my $dectot = 0;
-      while ($exprs =~ s/($expr_re),($dec_re)//) {
+      while ($exprs =~ s/($expr_re),\s*($dec_re)//) {
         my $dec = $6; $dec =~ s/--//g;
         next if !$dec || $dec eq '.';    # the contribution is 0!
         $dectot += $dec;
         push(@pallete, [DecodeColor($1), $dec]); }
       $div = $dectot unless $div;
       foreach my $cp (@pallete) {
+        # IMPORTANT: if we need to scale, first convert to RGB,
+        # or we risk losing scaling precision on any zero-valued components.
+        $$cp[0] = $$cp[0]->convert($color->model) unless $color->model eq $$cp[0]->model;
+        # now it is safe to scale:
         $color = $color->add($$cp[0]->scale($$cp[1] / $div)); } }
     else {    # Standard Color Expression: <prefix><name><mix_expr><postfix>
       $color = ($postfix && ($postfix =~ /!!\[(\d+)\]/)    # Note "out-of-order" effect!
diff --git a/t/graphics/xcolors.pdf b/t/graphics/xcolors.pdf
index a75da47827..6a81f92573 100644
Binary files a/t/graphics/xcolors.pdf and b/t/graphics/xcolors.pdf differ
diff --git a/t/graphics/xcolors.tex b/t/graphics/xcolors.tex
index 78362578c8..01d24f069c 100644
--- a/t/graphics/xcolors.tex
+++ b/t/graphics/xcolors.tex
@@ -252,4 +252,22 @@ \section{Boxes}
 \copy\mybox
 \setbox\mybox=\hbox{Should be Red!}
 {\color{red}\copy\mybox}
+
+\section{Custom rgb directives}
+\color{rgb:red,4;green,2;yellow,1} Brown
+
+\color{rgb:red,1;green,2;blue,5} Dark blue
+
+\color{rgb:orange,1;yellow,2;pink,5} Light orange
+
+\color{rgb:black,1;white,2} Gray
+
+\color{rgb, 255:red, 208; green, 2; blue, 27} Brick-like Red
+
+\color{rgb, 255:red, 74; green, 144; blue, 226} Ocean blue
+
+\color{rgb, 255:red, 0; green, 116; blue, 201} Sky blue
+
+\color{rgb, 255:red, 0; green, 0; blue, 0} Black
+
 \end{document}
diff --git a/t/graphics/xcolors.xml b/t/graphics/xcolors.xml
index 49d9d1bb2b..51179da56f 100644
--- a/t/graphics/xcolors.xml
+++ b/t/graphics/xcolors.xml
@@ -650,4 +650,36 @@ A=100*13 = 1300pt;</p>
 <text color="#FF0000">Should be Red!</text></p>
     </para>
   </section>
+  <section inlist="toc" xml:id="S12">
+    <tags>
+      <tag>12</tag>
+      <tag role="refnum">12</tag>
+      <tag role="typerefnum">§12</tag>
+    </tags>
+    <title><tag close=" ">12</tag>Custom rgb directives</title>
+    <para xml:id="S12.p1">
+      <p><text color="#B66D00">Brown</text></p>
+    </para>
+    <para xml:id="S12.p2">
+      <p><text color="#20409F">Dark blue</text></p>
+    </para>
+    <para xml:id="S12.p3">
+      <p><text color="#FFC778">Light orange</text></p>
+    </para>
+    <para xml:id="S12.p4">
+      <p><text color="#AAAAAA">Gray</text></p>
+    </para>
+    <para xml:id="S12.p5">
+      <p><text color="#D0021B">Brick-like Red</text></p>
+    </para>
+    <para xml:id="S12.p6">
+      <p><text color="#4A90E2">Ocean blue</text></p>
+    </para>
+    <para xml:id="S12.p7">
+      <p><text color="#0074C9">Sky blue</text></p>
+    </para>
+    <para xml:id="S12.p8">
+      <p><text color="#000000">Black</text></p>
+    </para>
+  </section>
 </document>