diff --git a/distutils/command/install.py b/distutils/command/install.py
index 8421d54e..6d8169e4 100644
--- a/distutils/command/install.py
+++ b/distutils/command/install.py
@@ -142,7 +142,7 @@ def _remove_set(ob, attrs):
 def _resolve_scheme(name):
     os_name, sep, key = name.partition('_')
     try:
-        resolved = sysconfig.get_preferred_scheme(key)
+        resolved = sysconfig.get_preferred_scheme(key or "prefix")
     except Exception:
         resolved = fw.scheme(name)
     return resolved