diff --git a/.github/tl_packages b/.github/tl_packages
index ada5da56..700edc5d 100644
--- a/.github/tl_packages
+++ b/.github/tl_packages
@@ -61,6 +61,7 @@ lualatex-math
 luatexbase
 luatexko
 makeindex
+mathastext
 mathpazo
 multirow
 natbib
diff --git a/CHANGELOG.md b/CHANGELOG.md
index c514b339..d81fcbf1 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -11,6 +11,10 @@ Changelog](https://keepachangelog.com/en/1.0.0/), and this project adheres to
 - Adjust `colortbl` support to allow for `tabularray` (see
   https://github.com/lvjr/tabularray/issues/512)
 
+### Fixed
+- Output of `\ohm` with `mathastext` (see issue
+  [\#757](https://github.com/josephwright/siunitx/issues/757))
+
 ## [v3.3.22] - 2024-09-30
 
 ### Fixed
diff --git a/siunitx-symbol.dtx b/siunitx-symbol.dtx
index ea974318..eb31aafa 100644
--- a/siunitx-symbol.dtx
+++ b/siunitx-symbol.dtx
@@ -243,16 +243,23 @@
                     \@ifpackageloaded { fontspec }
                       { \exp_not:V \l_@@_tmpb_tl }
                       {
-                        \bool_lazy_or:nnTF
+                        \bool_lazy_any:nTF
                           {
-                            \@ifclassloaded { beamer }
-                              \c_true_bool
-                              \c_false_bool
-                          }
-                          {
-                            \@ifpackageloaded { kmath }
-                              \c_true_bool
-                              \c_false_bool
+                            {
+                              \@ifclassloaded { beamer }
+                                \c_true_bool
+                                \c_false_bool
+                             }
+                             {
+                               \@ifpackageloaded { kmath }
+                                 \c_true_bool
+                                 \c_false_bool
+                              }
+                             {
+                               \@ifpackageloaded { mathastext }
+                                 \c_true_bool
+                                 \c_false_bool
+                              }
                           }
                           { \exp_not:V \l_@@_tmpb_tl }
                           { \exp_not:V \l_@@_tmpa_tl }
diff --git a/testfiles/siunitx-pkg-mathastext.lvt b/testfiles/siunitx-pkg-mathastext.lvt
new file mode 100644
index 00000000..9c81b879
--- /dev/null
+++ b/testfiles/siunitx-pkg-mathastext.lvt
@@ -0,0 +1,28 @@
+\input{regression-test}
+
+\documentclass{article}
+
+\ExplSyntaxOn
+\debug_on:n { check-declarations , deprecation }
+\ExplSyntaxOff
+
+\usepackage{siunitx}
+
+% Needed to force the failure we are testing for
+\ifdefined\Umathcode\else
+  \usepackage[T1]{fontenc}
+\fi
+\usepackage[LGRgreek]{mathastext}
+
+\begin{document}
+
+% Set up math fonts
+\savebox0{$ \mathrm { a } \mathsf { b } \mathtt{ c } \mathbf { d } $ }
+
+\START
+
+\showoutput
+
+\unit{\omega}
+
+\end{document}
diff --git a/testfiles/siunitx-pkg-mathastext.tlg b/testfiles/siunitx-pkg-mathastext.tlg
new file mode 100644
index 00000000..ef92770b
--- /dev/null
+++ b/testfiles/siunitx-pkg-mathastext.tlg
@@ -0,0 +1,46 @@
+This is a generated file for the l3build validation system.
+Don't change this file in any respect.
+Completed box being shipped out [1]
+\vbox(633.0+0.0)x407.0
+.\hbox(0.0+0.0)x0.0
+..\kern -72.26999
+..\vbox(0.0+0.0)x0.0, glue set 72.26999fil
+...\kern -72.26999
+...\hbox(0.0+0.0)x0.0
+....\glue 0.0 plus 1.0fil minus 1.0fil
+...\glue 0.0 plus 1.0fil minus 1.0fil
+.\glue 16.0
+.\vbox(617.0+0.0)x345.0, shifted 62.0
+..\vbox(12.0+0.0)x345.0, glue set 12.0fil
+...\glue 0.0 plus 1.0fil
+...\hbox(0.0+0.0)x345.0
+....\pdfcolorstack 0 push {0 g 0 G}
+....\hbox(0.0+0.0)x345.0
+....\pdfcolorstack 0 pop
+..\glue 25.0
+..\glue(\lineskip) 0.0
+..\vbox(550.0+0.0)x345.0, glue set 539.94232fil
+...\write-{}
+...\glue(\topskip) 5.6955
+...\hbox(4.3045+0.0)x345.0, glue set 322.64069fil
+....\hbox(0.0+0.0)x15.0
+....\mathon
+....\T1/cmr/m/n/10 w
+....\kern0.13885
+....\mathoff
+....\penalty 10000
+....\glue(\parfillskip) 0.0 plus 1.0fil
+....\glue(\rightskip) 0.0
+...\glue 0.0 plus 1.0fil
+...\glue 0.0
+...\glue 0.0 plus 0.0001fil
+..\glue(\baselineskip) 23.5849
+..\hbox(6.4151+0.0)x345.0
+...\pdfcolorstack 0 push {0 g 0 G}
+...\hbox(6.4151+0.0)x345.0, glue set 170.00061fil
+....\glue 0.0 plus 1.0fil
+....\T1/cmr/m/n/10 1
+....\glue 0.0 plus 1.0fil
+...\pdfcolorstack 0 pop
+.\kern 0.0
+(siunitx-pkg-mathastext.aux)