diff --git a/PC/os2vacpp/getpathp.c b/PC/os2vacpp/getpathp.c
index 69e38cb814f..d45c2f7a72c 100644
--- a/PC/os2vacpp/getpathp.c
+++ b/PC/os2vacpp/getpathp.c
@@ -389,7 +389,7 @@ calculate_path()
 	}
 	else
 		bufsz = 0;
-	bufsz += strlen(PYTHONPATH);
+	bufsz += strlen(PYTHONPATH) + 1;
 	if (envpath != NULL)
 		bufsz += strlen(envpath) + 1;
 	bufsz += strlen(argv0_path) + 1;