diff --git a/glicid/packages/mpi.scm b/glicid/packages/mpi.scm
index 4aef1c7..cc4f1a8 100644
--- a/glicid/packages/mpi.scm
+++ b/glicid/packages/mpi.scm
@@ -118,11 +118,13 @@
 (define gcc11-instead-of-gcc
   ;; This is a procedure to replace GCC by GCC11,
   ;; recursively.
+;  (package-input-rewriting/spec `((,gcc-toolchain . ,(const gcc-toolchain-11)))))
   (package-input-rewriting `((,gcc-toolchain . ,gcc-toolchain-11))))
 
 (define gcc10-instead-of-gcc
   ;; This is a procedure to replace GCC by GCC10,
   ;; recursively.
+;  (package-input-rewriting/spec `((,gcc-toolchain . ,(const gcc-toolchain-10)))))
   (package-input-rewriting `((,gcc-toolchain . ,gcc-toolchain-10))))