--- a/gcc/gcc.c
+++ b/gcc/gcc.c
@@ -7855,7 +7855,10 @@ getenv_spec_function (int argc, const ch
 
   value = getenv (argv[0]);
   if (!value)
-    fatal ("environment variable \"%s\" not defined", argv[0]);
+  {
+    error ("warning: environment variable \"%s\" not defined", argv[0]);
+    value = "";
+  }
 
   /* We have to escape every character of the environment variable so
      they are not interpreted as active spec characters.  A
