diff --git a/Lib/sysconfig.py b/Lib/sysconfig.py
index 91298d1..03f2d5c 100644
--- a/Lib/sysconfig.py
+++ b/Lib/sysconfig.py
@@ -432,6 +432,8 @@
 
         if 'srcdir' not in _CONFIG_VARS:
             _CONFIG_VARS['srcdir'] = _PROJECT_BASE
+        else:
+            _CONFIG_VARS['srcdir'] = realpath(_CONFIG_VARS['srcdir'])
 
 
         # Convert srcdir into an absolute path if it appears necessary.