diff --git a/src/Text/Pandoc/Readers/LaTeX/SIunitx.hs b/src/Text/Pandoc/Readers/LaTeX/SIunitx.hs
index 1952f4e1a..c4fb06700 100644
--- a/src/Text/Pandoc/Readers/LaTeX/SIunitx.hs
+++ b/src/Text/Pandoc/Readers/LaTeX/SIunitx.hs
@@ -45,7 +45,9 @@ doSI tok = do
                       unit]
 
 doSInum :: PandocMonad m => LP m Inlines
-doSInum = skipopts *> (tonum . untokenize <$> braced)
+doSInum = skipopts *> (tonum . untokenize . map convertPM <$> braced)
+  where convertPM (Tok pos (CtrlSeq "pm") _) = Tok pos Word "\xb1\xa0"
+        convertPM t = t
 
 tonum :: Text -> Inlines
 tonum value =
diff --git a/test/command/6620.md b/test/command/6620.md
index 314200d30..00643e57c 100644
--- a/test/command/6620.md
+++ b/test/command/6620.md
@@ -7,9 +7,12 @@
 \SI{0.135(21)}{\m}
 
 \SI{12.3(60)}{\m}
+
+\SI{10.0 \pm 3.3}{\ms}
 ^D
 <p>23 ± 2 m</p>
 <p>125 ± 12 m</p>
 <p>0.135 ± 0.021 m</p>
 <p>12.3 ± 6 m</p>
+<p>10.0 ± 3.3 ms</p>
 ```