Copy the change from ../getpathp.c here.

gvanrossum · gvanrossum · commit d0ec7616ea8f · 1997-12-11T15:21:33.000Z
diff --git 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;
