diff --git a/include/mimalloc-types.h b/include/mimalloc-types.h
index d4c1e1c1..3cdc4963 100644
--- a/include/mimalloc-types.h
+++ b/include/mimalloc-types.h
@@ -227,7 +227,7 @@ typedef enum mi_segment_kind_e {
   MI_SEGMENT_HUGE,   // > MI_LARGE_SIZE_MAX segment with just one huge page inside.
 } mi_segment_kind_t;
 
-#define MI_COMMIT_SIZE      (2UL<<20)   // OS large page size
+#define MI_COMMIT_SIZE      (1UL<<20)   // OS large page size
 
 #if ((1 << MI_SEGMENT_SHIFT)/MI_COMMIT_SIZE > 8*MI_INTPTR_SIZE)
 #error "not enough commit bits to cover the segment size"
diff --git a/src/arena.c b/src/arena.c
index c1b47073..f3dd690f 100644
--- a/src/arena.c
+++ b/src/arena.c
@@ -203,7 +203,7 @@ static void mi_cache_purge(mi_os_tld_t* tld) {
     void* p = mi_atomic_read_ptr_relaxed(&slot->p);
     if (p > MI_SLOT_IN_USE && !slot->is_committed && !slot->is_large) {
       mi_msecs_t expire = slot->expire;
-      if (now >= expire) {
+      if (expire != 0 && now >= expire) {
         // expired, try to claim it
         if (mi_atomic_cas_ptr_weak(&slot->p, MI_SLOT_IN_USE, p)) {
           // claimed! test again
diff --git a/src/options.c b/src/options.c
index 6fd887a3..dcee89e6 100644
--- a/src/options.c
+++ b/src/options.c
@@ -64,7 +64,7 @@ static mi_option_desc_t options[_mi_option_last] =
   { 0, UNINIT, MI_OPTION(segment_reset) },       // reset segment memory on free (needs eager commit)
   { 1, UNINIT, MI_OPTION(reset_decommits) },     // reset decommits memory
   { 0, UNINIT, MI_OPTION(eager_commit_delay) },  // the first N segments per thread are not eagerly committed
-  { 0, UNINIT, MI_OPTION(allow_decommit) },      // decommit pages when not eager committed
+  { 1, UNINIT, MI_OPTION(allow_decommit) },      // decommit pages when not eager committed
   { 1000, UNINIT, MI_OPTION(reset_delay) },       // reset delay in milli-seconds
   { 1000, UNINIT, MI_OPTION(arena_reset_delay) }, // reset delay in milli-seconds
   { 0,    UNINIT, MI_OPTION(use_numa_nodes) },    // 0 = use available numa nodes, otherwise use at most N nodes. 
diff --git a/src/segment.c b/src/segment.c
index 042ce2b7..d0580b74 100644
--- a/src/segment.c
+++ b/src/segment.c
@@ -381,6 +381,7 @@ static uintptr_t mi_segment_commit_mask(mi_segment_t* segment, bool conservative
   mi_assert_internal(start % MI_COMMIT_SIZE==0 && end % MI_COMMIT_SIZE == 0);
   *start_p   = (uint8_t*)segment + start;
   *full_size = (end > start ? end - start : 0);
+  if (*full_size == 0) return 0;
 
   uintptr_t bitidx = start / MI_COMMIT_SIZE;
   mi_assert_internal(bitidx < (MI_INTPTR_SIZE*8));
@@ -931,8 +932,7 @@ bool _mi_segment_try_reclaim_abandoned( mi_heap_t* heap, bool try_all, mi_segmen
     mi_segments_track_size((long)mi_segment_size(segment),tld);
     mi_assert_internal(segment->next == NULL);
     _mi_stat_decrease(&tld->stats->segments_abandoned,1);
-    mi_assert_internal(segment->decommit_mask == 0);
-
+    //mi_assert_internal(segment->decommit_mask == 0);
 
     mi_slice_t* slice = &segment->slices[0];
     const mi_slice_t* end = mi_segment_slices_end(segment);