diff --git a/relalg.sty b/relalg.sty
index 8941b1a..ec2c2f5 100644
--- a/relalg.sty
+++ b/relalg.sty
@@ -1,6 +1,6 @@
-\def\packagedate{13 December 2024}
-\def\packageversion{2.0}
-\def\packageshortdate{2024/12/13}
+\def\packagedate{15 Jamuary 2025}
+\def\packageversion{2.1}
+\def\packageshortdate{2025/01/15}
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 %
 % Defines various relational algebra symbols.
@@ -10,6 +10,8 @@
 % Version History
 % v1.0    Initial version.
 % v2.0    Complete rewrite to support Unicode OpenType fonts and LaTeX3.
+% v2.1    Plays nicely with other packages that \setmathfont, and only
+%         interpolates join symbols if they aren’t in the current font.
 %
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
@@ -24,32 +26,38 @@
 
 
 \ExplSyntaxOn
-    \bool_new:N \__unicode_engine
+    \bool_new:N \g__ra_unicode_engine
 
     \ifLuaTeX
         \PackageInfo{relalg}{LuaTeX\space engine\space detected}
-        \bool_set_true:N \__unicode_engine
+        \bool_set_true:N \g__ra_unicode_engine
     \fi
 
     \ifXeTeX
         \PackageInfo{relalg}{XeTeX\space engine\space detected}
-        \bool_set_true:N \__unicode_engine
+        \bool_set_true:N \g__ra_unicode_engine
     \fi
 
-    \bool_if:NTF \__unicode_engine {
+    \bool_if:NTF \g__ra_unicode_engine {
         \RequirePackage[no-math]{fontspec}
         \RequirePackage{unicode-math}
 
-        \setmathfont{latinmodern-math.otf}
+        % Stolen from unicode-math.sty as the fallback in unicode-math doesn't
+        % seem to work? Weirdly it seems to work in a bare-bones MWE.
+        \bool_if:NF \g__um_main_font_defined_bool \__um_load_lm:
 
         % The various join symbols aren't covered very well by many maths fonts
-        % (including Latin Modern Math, annoyingly), so let's Frankenstein them
-        % in from fonts that do have them. We need to hack the scale to get roughly
-        % proportional looking sizes.
+        % (including Latin Modern Math, annoyingly), so if necessary let's
+        % Frankenstein them in from fonts that do have them. We need to hack
+        % the scale to get roughly proportional looking sizes.
+        % \iffontchar trick from <https://tex.stackexchange.com/questions/642080/newunicodechar-only-if-undeclared>
         % Outer joins (left, right, full):
-        \setmathfont{STIXTwoMath-Regular.otf}[range={"027D5-"027D7}, Scale=0.875]
+        \iffontchar\font "27D5\relax\else\setmathfont{STIXTwoMath-Regular.otf}[range="027D5, Scale=0.875]
+        \iffontchar\font "27D6\relax\else\setmathfont{STIXTwoMath-Regular.otf}[range="27D6, Scale=0.875]
+        \iffontchar\font "27D7\relax\else\setmathfont{STIXTwoMath-Regular.otf}[range="27D7, Scale=0.875]
+        % \setmathfont{STIXTwoMath-Regular.otf}[range={"027D5-"027D7}, Scale=0.875]
         % Inner join: (1.143 = 1 / 0.875)
-        \setmathfont{KpMath-Light.otf}[range={"02A1D}, Scale=1.143]
+        \iffontchar\font "2A1D\relax\else\setmathfont{KpMath-Light.otf}[range="2A1D, Scale=1.143]
     }{
         \PackageInfo{relalg}{non-Unicode\space engine\space detected}
         \RequirePackage{latexsym} % for \Join
@@ -177,7 +185,7 @@
 
 % Outer join operators.
 \ExplSyntaxOn
-    \bool_if:NTF \__unicode_engine {
+    \bool_if:NTF \g__ra_unicode_engine {
         \NewDocumentCommand{\RelLeftOuterJoin}{}{\ensuremath{\ifXeTeX\mkern2.5mu\fi\mathbin{\leftouterjoin}}}
         \NewDocumentCommand{\RelRightOuterJoin}{}{\ensuremath{\ifXeTeX\mkern2.5mu\fi\mathbin{\rightouterjoin}}}
         \NewDocumentCommand{\RelFullOuterJoin}{}{\ensuremath{\ifXeTeX\mkern2.5mu\fi\mathbin{\fullouterjoin}}}
@@ -187,10 +195,10 @@
         % Weirdly the height of \Join is fractionally shorter than \bowtie, so
         % we can't use the more sensible solution of measuring off the line
         % height. Use only font-relative units to ensure proper scaling.
-        \def\__ojoin{\rule[0.11ex]{0.25em}{0.1ex}\llap{\rule[1.41ex]{0.25em}{0.1ex}}}
-        \NewDocumentCommand{\RelLeftOuterJoin}{}{\ensuremath{\mathbin{\__ojoin\mkern-6.4mu\Join}}}
-        \NewDocumentCommand{\RelRightOuterJoin}{}{\ensuremath{\mathbin{\Join\mkern-6.4mu\__ojoin}}}
-        \NewDocumentCommand{\RelFullOuterJoin}{}{\ensuremath{\mathbin{\__ojoin\mkern-6.4mu\Join\mkern-6.4mu\__ojoin}}}
+        \def\__ra_outer_join{\rule[0.11ex]{0.25em}{0.1ex}\llap{\rule[1.41ex]{0.25em}{0.1ex}}}
+        \NewDocumentCommand{\RelLeftOuterJoin}{}{\ensuremath{\mathbin{\__ra_outer_join\mkern-6.4mu\Join}}}
+        \NewDocumentCommand{\RelRightOuterJoin}{}{\ensuremath{\mathbin{\Join\mkern-6.4mu\__ra_outer_join}}}
+        \NewDocumentCommand{\RelFullOuterJoin}{}{\ensuremath{\mathbin{\__ra_outer_join\mkern-6.4mu\Join\mkern-6.4mu\__ra_outer_join}}}
     }
 \ExplSyntaxOff