diff --git a/build-and-test-py-project.sh b/build-and-test-py-project.sh
index 69b5b8e52030ce6724392b5f0261687ada3301b5..0810a3871a048bb83a6f317e6eba1fbc8dc00fa3 100644
--- a/build-and-test-py-project.sh
+++ b/build-and-test-py-project.sh
@@ -59,6 +59,26 @@ $PIP install setuptools
 # Install before a newer version gets pulled in as a dependency
 $PIP install pytest==3.0.4 pytest-warnings==0.2.0
 
+if test "$EXTRA_INSTALL" != ""; then
+  for i in $EXTRA_INSTALL ; do
+    if [ "$i" = "numpy" ] && [[ "${PY_EXE}" == pypy* ]]; then
+      $PIP install git+https://bitbucket.org/pypy/numpy.git
+    elif [[ "$i" = *pybind11* ]] && [[ "${PY_EXE}" == pypy* ]]; then
+      # Work around https://github.com/pypa/virtualenv/issues/1198
+      # Running virtualenv --always-copy or -m venv --copies should also do the trick.
+      L=$(readlink .env/include)
+      rm .env/include
+      cp -R $L .env/include
+
+      $PIP install $i
+    elif [ "$i" = "numpy" ] && [[ "${PY_EXE}" == python2.6* ]]; then
+      $PIP install 'numpy==1.10.4'
+    else
+      $PIP install $i
+    fi
+  done
+fi
+
 if test "$REQUIREMENTS_TXT" == ""; then
   REQUIREMENTS_TXT="requirements.txt"
 fi