diff --git a/sphinx/ext/imgmath.py b/sphinx/ext/imgmath.py
index 5bfca8d4d03..ddef581870a 100644
--- a/sphinx/ext/imgmath.py
+++ b/sphinx/ext/imgmath.py
@@ -308,7 +308,7 @@ def html_visit_math(self: HTMLTranslator, node: nodes.math) -> None:
         raise nodes.SkipNode from exc
     if self.builder.config.imgmath_embed:
         image_format = self.builder.config.imgmath_image_format.lower()
-        img_src = render_maths_to_base64(image_format, outfn)
+        img_src = render_maths_to_base64(image_format, imgpath)
     else:
         # Move generated image on tempdir to build dir
         if imgpath is not None:
@@ -350,7 +350,7 @@ def html_visit_displaymath(self: HTMLTranslator, node: nodes.math_block) -> None
         self.body.append('</span>')
     if self.builder.config.imgmath_embed:
         image_format = self.builder.config.imgmath_image_format.lower()
-        img_src = render_maths_to_base64(image_format, outfn)
+        img_src = render_maths_to_base64(image_format, imgpath)
     else:
         # Move generated image on tempdir to build dir
         if imgpath is not None:
diff --git a/tests/test_ext_math.py b/tests/test_ext_math.py
index 7b11ea3be56..855bef3059e 100644
--- a/tests/test_ext_math.py
+++ b/tests/test_ext_math.py
@@ -1,6 +1,7 @@
 """Test math extensions."""
 
 import re
+import shutil
 import subprocess
 import warnings
 
@@ -33,6 +34,7 @@ def test_imgmath_png(app, status, warning):
         raise pytest.skip.Exception('dvipng command "dvipng" is not available')
 
     content = (app.outdir / 'index.html').read_text(encoding='utf8')
+    shutil.rmtree(app.outdir)
     html = (r'<div class="math">\s*<p>\s*<img src="_images/math/\w+.png"'
             r'\s*alt="a\^2\+b\^2=c\^2"/>\s*</p>\s*</div>')
     assert re.search(html, content, re.S)
@@ -51,6 +53,7 @@ def test_imgmath_svg(app, status, warning):
         raise pytest.skip.Exception('dvisvgm command "dvisvgm" is not available')
 
     content = (app.outdir / 'index.html').read_text(encoding='utf8')
+    shutil.rmtree(app.outdir)
     html = (r'<div class="math">\s*<p>\s*<img src="_images/math/\w+.svg"'
             r'\s*alt="a\^2\+b\^2=c\^2"/>\s*</p>\s*</div>')
     assert re.search(html, content, re.S)
@@ -70,6 +73,7 @@ def test_imgmath_svg_embed(app, status, warning):
         pytest.skip('dvisvgm command "dvisvgm" is not available')
 
     content = (app.outdir / 'index.html').read_text(encoding='utf8')
+    shutil.rmtree(app.outdir)
     html = r'<img src="data:image/svg\+xml;base64,[\w\+/=]+"'
     assert re.search(html, content, re.DOTALL)