diff --git a/src/hb-ot-math-table.hh b/src/hb-ot-math-table.hh
index c2e365dbd..8d0b4317c 100644
--- a/src/hb-ot-math-table.hh
+++ b/src/hb-ot-math-table.hh
@@ -511,7 +511,8 @@ struct MathGlyphInfo
     | hb_map_retains_sorting (glyph_map)
     ;
 
-    out->extendedShapeCoverage.serialize_serialize (c->serializer, it);
+    if (it) out->extendedShapeCoverage.serialize_serialize (c->serializer, it);
+    else out->extendedShapeCoverage = 0;
 
     out->mathKernInfo.serialize_subset (c, mathKernInfo, this);
     return_trace (true);
@@ -884,8 +885,11 @@ struct MathVariants
       if (!o) return_trace (false);
       o->serialize_subset (c, glyphConstruction[i], this);
     }
-
-    out->vertGlyphCoverage.serialize_serialize (c->serializer, new_vert_coverage.iter ());
+    
+    if (new_vert_coverage)
+      out->vertGlyphCoverage.serialize_serialize (c->serializer, new_vert_coverage.iter ());
+    
+    if (new_hori_coverage)
     out->horizGlyphCoverage.serialize_serialize (c->serializer, new_hori_coverage.iter ());
     return_trace (true);
   }
diff --git a/test/subset/data/Makefile.am b/test/subset/data/Makefile.am
index c2dff35e6..f9dd45bc9 100644
--- a/test/subset/data/Makefile.am
+++ b/test/subset/data/Makefile.am
@@ -52,6 +52,7 @@ EXTRA_DIST += \
 	expected/variable \
 	expected/glyph_names \
 	expected/math \
+	expected/math_coverage_offset \
 	expected/post \
 	fonts \
 	profiles \
diff --git a/test/subset/data/Makefile.sources b/test/subset/data/Makefile.sources
index 1a56e1e3d..20f334783 100644
--- a/test/subset/data/Makefile.sources
+++ b/test/subset/data/Makefile.sources
@@ -44,6 +44,7 @@ TESTS = \
 	tests/variable.tests \
 	tests/glyph_names.tests \
 	tests/math.tests \
+	tests/math_coverage_offset.tests \
 	tests/post.tests \
 	$(NULL)
 
diff --git a/test/subset/data/expected/math_coverage_offset/Caudex-Regular.default.retain-all-codepoint.ttf b/test/subset/data/expected/math_coverage_offset/Caudex-Regular.default.retain-all-codepoint.ttf
new file mode 100644
index 000000000..0df9dca60
Binary files /dev/null and b/test/subset/data/expected/math_coverage_offset/Caudex-Regular.default.retain-all-codepoint.ttf differ
diff --git a/test/subset/data/expected/math_coverage_offset/Caudex-Regular.glyph-names.retain-all-codepoint.ttf b/test/subset/data/expected/math_coverage_offset/Caudex-Regular.glyph-names.retain-all-codepoint.ttf
new file mode 100644
index 000000000..6686d486b
Binary files /dev/null and b/test/subset/data/expected/math_coverage_offset/Caudex-Regular.glyph-names.retain-all-codepoint.ttf differ
diff --git a/test/subset/data/expected/math_coverage_offset/Caudex-Regular.keep-all-layout-features.retain-all-codepoint.ttf b/test/subset/data/expected/math_coverage_offset/Caudex-Regular.keep-all-layout-features.retain-all-codepoint.ttf
new file mode 100644
index 000000000..0df9dca60
Binary files /dev/null and b/test/subset/data/expected/math_coverage_offset/Caudex-Regular.keep-all-layout-features.retain-all-codepoint.ttf differ
diff --git a/test/subset/data/expected/math_coverage_offset/Caudex-Regular.notdef-outline.retain-all-codepoint.ttf b/test/subset/data/expected/math_coverage_offset/Caudex-Regular.notdef-outline.retain-all-codepoint.ttf
new file mode 100644
index 000000000..1ce1535e5
Binary files /dev/null and b/test/subset/data/expected/math_coverage_offset/Caudex-Regular.notdef-outline.retain-all-codepoint.ttf differ
diff --git a/test/subset/data/expected/math_coverage_offset/Caudex-Regular.retain-gids.retain-all-codepoint.ttf b/test/subset/data/expected/math_coverage_offset/Caudex-Regular.retain-gids.retain-all-codepoint.ttf
new file mode 100644
index 000000000..f46479b26
Binary files /dev/null and b/test/subset/data/expected/math_coverage_offset/Caudex-Regular.retain-gids.retain-all-codepoint.ttf differ
diff --git a/test/subset/data/fonts/Caudex-Regular.ttf b/test/subset/data/fonts/Caudex-Regular.ttf
new file mode 100644
index 000000000..669f9f8c9
Binary files /dev/null and b/test/subset/data/fonts/Caudex-Regular.ttf differ
diff --git a/test/subset/data/tests/math_coverage_offset.tests b/test/subset/data/tests/math_coverage_offset.tests
new file mode 100644
index 000000000..ac333b7be
--- /dev/null
+++ b/test/subset/data/tests/math_coverage_offset.tests
@@ -0,0 +1,12 @@
+FONTS:
+Caudex-Regular.ttf
+
+PROFILES:
+default.txt
+retain-gids.txt
+glyph-names.txt
+notdef-outline.txt
+keep-all-layout-features.txt
+
+SUBSETS:
+*
diff --git a/test/subset/meson.build b/test/subset/meson.build
index c75106caf..fb27ffcd3 100644
--- a/test/subset/meson.build
+++ b/test/subset/meson.build
@@ -39,6 +39,7 @@ tests = [
   'sbix',
   'colr',
   'math',
+  'math_coverage_offset',
 # TODO: re-enable once colrv1 subsetting is stabilized.
 # 'colrv1.notoemoji',
   'colrv1',