diff --git a/src/mpi/f77/group_free_f.c b/src/mpi/f77/group_free_f.c
index 5b3c7aa04f..f803a28687 100644
--- a/src/mpi/f77/group_free_f.c
+++ b/src/mpi/f77/group_free_f.c
@@ -52,11 +52,12 @@ void mpi_group_free_f(MPI_Fint *group, MPI_Fint *ierr)
   ompi_group_t *c_group;
 
   /* Make the fortran to c representation conversion */
+
   c_group = MPI_Group_f2c(*group);
- 
   *ierr = MPI_Group_free( &c_group );
 
-  if(*ierr == OMPI_SUCCESS) 
-    *group = 0;
+  /* This value comes from the MPI_GROUP_NULL value in mpif.h.  Do not
+     change without consulting mpif.h! */
 
+  *group = 0;
 }
diff --git a/src/mpi/f77/is_thread_main_f.c b/src/mpi/f77/is_thread_main_f.c
index b301fce3f2..71e3a6f543 100644
--- a/src/mpi/f77/is_thread_main_f.c
+++ b/src/mpi/f77/is_thread_main_f.c
@@ -48,5 +48,5 @@ OMPI_GENERATE_F77_BINDINGS (MPI_IS_THREAD_MAIN,
 
 void mpi_is_thread_main_f(MPI_Fint *flag, MPI_Fint *ierr)
 {
-    *ierr = MPI_Is_thread_main( (int)flag );
+    *ierr = MPI_Is_thread_main( flag );
 }
diff --git a/src/mpi/f77/request_free_f.c b/src/mpi/f77/request_free_f.c
index 57b1040404..f72e5cbdbd 100644
--- a/src/mpi/f77/request_free_f.c
+++ b/src/mpi/f77/request_free_f.c
@@ -49,8 +49,10 @@ OMPI_GENERATE_F77_BINDINGS (MPI_REQUEST_FREE,
 void mpi_request_free_f(MPI_Fint *request, MPI_Fint *ierr)
 {
     MPI_Request c_req = MPI_Request_f2c( *request ); 
-
     *ierr = MPI_Request_free( &c_req );
 
-    *request = (MPI_Fint)MPI_REQUEST_NULL;
+    /* This value comes from the MPI_REQUEST_NULL value in mpif.h.
+       Do not change without consulting mpif.h! */
+
+    *request = -1;
 }
diff --git a/src/mpi/f77/type_free_f.c b/src/mpi/f77/type_free_f.c
index 221bf5c0d1..7520c6894b 100644
--- a/src/mpi/f77/type_free_f.c
+++ b/src/mpi/f77/type_free_f.c
@@ -49,9 +49,10 @@ OMPI_GENERATE_F77_BINDINGS (MPI_TYPE_FREE,
 void mpi_type_free_f(MPI_Fint *type, MPI_Fint *ierr)
 {
     MPI_Datatype c_type = MPI_DATATYPE_NULL;
-
     *ierr = MPI_Type_free(&c_type);
 
-    if( *ierr == MPI_SUCCESS )
-      type = (MPI_Fint)MPI_DATATYPE_NULL;
+    /* This value comes from the MPI_DATATYPE_NULL value in mpif.h.
+       Do not change without consulting mpif.h! */
+
+    *type = -1;
 }