diff --git a/requirements.txt b/requirements.txt
index d171fe83b62e11a38a871698ab3337d0ae255e05..d23294370a2fe408220c6e74eedd7b3e4bcd54ce 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -3,6 +3,7 @@ git+git://github.com/inducer/modepy
 git+git://github.com/pyopencl/pyopencl
 git+git://github.com/inducer/loopy
 
-# required by pytential
+# required by pytential, which is in turn needed for some tests
+git+git://github.com/inducer/sumpy
 git+git://github.com/inducer/boxtree
 git+git://github.com/inducer/pytential