diff --git a/common.sh b/common.sh
index a97c560fe8..6f6aa00435 100644
--- a/common.sh
+++ b/common.sh
@@ -843,8 +843,8 @@ reinterpret_path_for_chroot() {
 # Get the relative path between two locations. Handy for printing paths to
 # the user that will usually make sense both inside and outside the chroot.
 relpath() {
-  local py='import sys, os; print os.path.relpath(sys.argv[1], sys.argv[2])'
-  python2 -c "${py}" "${1}" "${2:-.}"
+  local py='import sys, os; print(os.path.relpath(sys.argv[1], sys.argv[2]))'
+  python3 -c "${py}" "${1}" "${2:-.}"
 }
 
 enable_strict_sudo() {