diff --git a/ptx/sec_IBP.ptx b/ptx/sec_IBP.ptx
index 68c7d2a94..b3629c338 100644
--- a/ptx/sec_IBP.ptx
+++ b/ptx/sec_IBP.ptx
@@ -474,7 +474,7 @@
           <p>
             <md>
               <mrow>u\amp = e^x \amp  v\amp =\sin(x)</mrow>
-              <mrow>du\amp = e^x  \amp  dv\amp =\cos(x) \, dx</mrow>
+              <mrow>du\amp = e^x \, dx  \amp  dv\amp =\cos(x) \, dx</mrow>
             </md>
           </p>
         </sidebyside>