diff --git a/src/comp.c b/src/comp.c
index 7de222b5b2b..ede417c794f 100644
--- a/src/comp.c
+++ b/src/comp.c
@@ -1540,7 +1540,8 @@ DEFUN ("native-compile", Fnative_compile, Snative_compile,
   char *c = c_f_name;
   while (*c)
     {
-      if (*c == '-')
+      if (*c == '-' ||
+	  *c == '+')
 	*c = '_';
       ++c;
     }