diff --git a/src/common/execio.c b/src/common/execio.c
--- a/src/common/execio.c
+++ b/src/common/execio.c
@@ -165,7 +165,7 @@ int _execio_checkpid(struct execio *eio)
 }
 
 
-int execio_read(struct execio *eio, void *buf, size_t len, size_t *bytesread)
+int execio_read(struct execio *eio, const void *buf, size_t len, size_t *bytesread)
 {
   ssize_t ret;
   /*
@@ -203,7 +203,7 @@ int execio_read(struct execio *eio, void
   return 0;
 }
 
-int execio_write(struct execio *eio, void *buf, size_t len, size_t *bytesread)
+int execio_write(struct execio *eio, const void *buf, size_t len, size_t *bytesread)
 {
   errno = 0;
   (*bytesread) = write(eio->pipe_write, buf, len);