diff --git a/ompi/mca/coll/adapt/coll_adapt_ireduce.c b/ompi/mca/coll/adapt/coll_adapt_ireduce.c
index da6486401f9..b3f7877bbe7 100644
--- a/ompi/mca/coll/adapt/coll_adapt_ireduce.c
+++ b/ompi/mca/coll/adapt/coll_adapt_ireduce.c
@@ -45,7 +45,7 @@ int ompi_coll_adapt_ireduce_register(void)
         mca_coll_adapt_component.adapt_ireduce_algorithm = 1;
     }
 
-    mca_coll_adapt_component.adapt_ireduce_segment_size = 163740;
+    mca_coll_adapt_component.adapt_ireduce_segment_size = 524288;
     mca_base_component_var_register(c, "reduce_segment_size",
                                     "Segment size in bytes used by default for reduce algorithms. Only has meaning if algorithm is forced and supports segmenting. 0 bytes means no segmentation.",
                                     MCA_BASE_VAR_TYPE_SIZE_T, NULL, 0, 0,
diff --git a/ompi/mca/coll/han/coll_han_component.c b/ompi/mca/coll/han/coll_han_component.c
index 0f5c1a85d2c..642a3967982 100644
--- a/ompi/mca/coll/han/coll_han_component.c
+++ b/ompi/mca/coll/han/coll_han_component.c
@@ -261,7 +261,7 @@ static int han_register(void)
                                            OPAL_INFO_LVL_9,
                                            MCA_BASE_VAR_SCOPE_READONLY, &cs->han_output_verbose);
 
-    cs->han_bcast_segsize = 65536;
+    cs->han_bcast_segsize = 524288;
     (void) mca_base_component_var_register(c, "bcast_segsize",
                                            "segment size for bcast",
                                            MCA_BASE_VAR_TYPE_INT, NULL, 0, 0,
@@ -281,7 +281,7 @@ static int han_register(void)
                                               &cs->han_bcast_low_module,
                                               &cs->han_op_module_name.bcast.han_op_low_module_name);
 
-    cs->han_reduce_segsize = 65536;
+    cs->han_reduce_segsize = 524288;
     (void) mca_base_component_var_register(c, "reduce_segsize",
                                            "segment size for reduce",
                                            MCA_BASE_VAR_TYPE_INT, NULL, 0, 0,
@@ -300,7 +300,7 @@ static int han_register(void)
                                               OPAL_INFO_LVL_9, &cs->han_reduce_low_module,
                                               &cs->han_op_module_name.reduce.han_op_low_module_name);
 
-    cs->han_allreduce_segsize = 65536;
+    cs->han_allreduce_segsize = 524288;
     (void) mca_base_component_var_register(c, "allreduce_segsize",
                                            "segment size for allreduce",
                                            MCA_BASE_VAR_TYPE_INT, NULL, 0, 0,