diff --git a/ompi/mca/osc/sm/osc_sm_active_target.c b/ompi/mca/osc/sm/osc_sm_active_target.c
index ab0f73f87c6..e34389be6c7 100644
--- a/ompi/mca/osc/sm/osc_sm_active_target.c
+++ b/ompi/mca/osc/sm/osc_sm_active_target.c
@@ -151,7 +151,7 @@ ompi_osc_sm_start(struct ompi_group_t *group,
 
         for (int i = 0 ; i < size ; ++i) {
             int rank_byte = ranks[i] >> OSC_SM_POST_BITS;
-            osc_sm_post_type_t rank_bit = ((osc_sm_post_type_t) 1) << (ranks[i] & 0x3f);
+            osc_sm_post_type_t rank_bit = ((osc_sm_post_type_t) 1) << (ranks[i] & OSC_SM_POST_MASK);
 
             /* wait for rank to post */
             while (!(module->posts[my_rank][rank_byte] & rank_bit)) {
@@ -221,8 +221,8 @@ ompi_osc_sm_post(struct ompi_group_t *group,
     ompi_osc_sm_module_t *module =
         (ompi_osc_sm_module_t*) win->w_osc_module;
     int my_rank = ompi_comm_rank (module->comm);
-    int my_byte = my_rank >> 6;
-    uint64_t my_bit = ((uint64_t) 1) << (my_rank & 0x3f);
+    int my_byte = my_rank >> OSC_SM_POST_BITS;
+    osc_sm_post_type_t my_bit = ((osc_sm_post_type_t) 1) << (my_rank & OSC_SM_POST_MASK);
     int gsize;
 
     OPAL_THREAD_LOCK(&module->lock);
diff --git a/ompi/mca/osc/sm/osc_sm_component.c b/ompi/mca/osc/sm/osc_sm_component.c
index de891e71a11..0475e65266b 100644
--- a/ompi/mca/osc/sm/osc_sm_component.c
+++ b/ompi/mca/osc/sm/osc_sm_component.c
@@ -242,7 +242,7 @@ component_select(struct ompi_win_t *win, void **base, size_t size, int disp_unit
         int i, flag;
         size_t pagesize;
         size_t state_size;
-        size_t posts_size, post_size = (comm_size + 63) / 64;
+        size_t posts_size, post_size = (comm_size + OSC_SM_POST_MASK) / (OSC_SM_POST_MASK + 1);
 
         OPAL_OUTPUT_VERBOSE((1, ompi_osc_base_framework.framework_output,
                              "allocating shared memory region of size %ld\n", (long) size));