diff --git a/include/mimalloc-internal.h b/include/mimalloc-internal.h
index d0c0b3f3..35413315 100644
--- a/include/mimalloc-internal.h
+++ b/include/mimalloc-internal.h
@@ -263,7 +263,7 @@ static inline bool mi_count_size_overflow(size_t count, size_t size, size_t* tot
     return false;
   }
   else if (mi_unlikely(mi_mul_overflow(count, size, total))) {
-    _mi_error_message(EOVERFLOW, "allocation request too large (%zu * %zu bytes)\n", count, size);
+    _mi_error_message(EOVERFLOW, "allocation request is too large (%zu * %zu bytes)\n", count, size);
     *total = SIZE_MAX;
     return true;
   }
diff --git a/src/os.c b/src/os.c
index f33cfbc3..72214a9f 100644
--- a/src/os.c
+++ b/src/os.c
@@ -262,7 +262,7 @@ static void* mi_win_virtual_alloc(void* addr, size_t size, size_t try_alignment,
     p = mi_win_virtual_allocx(addr, size, try_alignment, flags);
   }
   if (p == NULL) {
-    _mi_warning_message("unable to allocate memory: error code: %i, addr: %p, size: 0x%x, large only: %d, allow_large: %d\n", GetLastError(), addr, size, large_only, allow_large);
+    _mi_warning_message("unable to allocate OS memory (%zu bytes, error code: %i, address: %p, large only: %d, allow large: %d)\n", size, GetLastError(), addr, large_only, allow_large);
   }
   return p;
 }
@@ -399,6 +399,9 @@ static void* mi_unix_mmap(void* addr, size_t size, size_t try_alignment, int pro
     }
     #endif
   }
+  if (p == NULL) {
+    _mi_warning_message("unable to allocate OS memory (%zu bytes, error code: %i, address: %p, large only: %d, allow large: %d)\n", size, errno, addr, large_only, allow_large);
+  }
   return p;
 }
 #endif
diff --git a/src/page.c b/src/page.c
index 08aa88c7..18f1812e 100644
--- a/src/page.c
+++ b/src/page.c
@@ -792,7 +792,7 @@ static mi_page_t* mi_find_page(mi_heap_t* heap, size_t size) mi_attr_noexcept {
   const size_t req_size = size - MI_PADDING_SIZE;  // correct for padding_size in case of an overflow on `size`  
   if (mi_unlikely(req_size > (MI_LARGE_OBJ_SIZE_MAX - MI_PADDING_SIZE) )) {
     if (mi_unlikely(req_size > PTRDIFF_MAX)) {  // we don't allocate more than PTRDIFF_MAX (see <https://sourceware.org/ml/libc-announce/2019/msg00001.html>)
-      _mi_error_message(EOVERFLOW, "allocation request is too large (%zu b requested)\n", req_size);
+      _mi_error_message(EOVERFLOW, "allocation request is too large (%zu bytes)\n", req_size);
       return NULL;
     }
     else {
@@ -833,7 +833,8 @@ void* _mi_malloc_generic(mi_heap_t* heap, size_t size) mi_attr_noexcept
   }
 
   if (mi_unlikely(page == NULL)) { // out of memory
-    _mi_error_message(ENOMEM, "cannot allocate memory (%zu bytes requested)\n", size);
+    const size_t req_size = size - MI_PADDING_SIZE;  // correct for padding_size in case of an overflow on `size`  
+    _mi_error_message(ENOMEM, "unable to allocate memory (%zu bytes)\n", req_size);
     return NULL;
   }