--- a/tests/run-tests
+++ b/tests/run-tests
@@ -40,16 +40,11 @@ HGTMP="${TMPDIR-/tmp}/hgtests.$RANDOM.$R
 }
 
 TESTDIR="$PWD"
-
-if [ -d /usr/lib64 ]; then
-    lib=lib64
-else
-    lib=lib
-fi
-
 INST="$HGTMP/install"
+PYTHONDIR="$INST/lib/python"
 cd ..
-if ${PYTHON-python} setup.py install --home="$INST" > tests/install.err 2>&1
+if ${PYTHON-python} setup.py install --home="$INST" \
+  --install-lib="$PYTHONDIR" > tests/install.err 2>&1
 then
     rm tests/install.err
 else
@@ -59,8 +54,7 @@ fi
 cd "$TESTDIR"
 
 PATH="$INST/bin:$PATH"; export PATH
-PYTHONPATH="$INST/$lib/python"; export PYTHONPATH
-
+PYTHONPATH="$PYTHONDIR"; export PYTHONPATH
 
 run_one() {
     rm -f "$1.err"