diff --git a/AK/HashTable.h b/AK/HashTable.h
index eac567a5d66..acfddf9b58e 100644
--- a/AK/HashTable.h
+++ b/AK/HashTable.h
@@ -258,6 +258,7 @@ private:
     void rehash(size_t new_capacity)
     {
         new_capacity = max(new_capacity, static_cast<size_t>(4));
+        new_capacity = kmalloc_good_size(new_capacity * sizeof(Bucket)) / sizeof(Bucket);
 
         auto* old_buckets = m_buckets;
         auto old_capacity = m_capacity;
diff --git a/AK/Vector.h b/AK/Vector.h
index 74601a2a89c..7acc9bdd154 100644
--- a/AK/Vector.h
+++ b/AK/Vector.h
@@ -563,7 +563,7 @@ public:
     {
         if (m_capacity >= needed_capacity)
             return true;
-        size_t new_capacity = needed_capacity;
+        size_t new_capacity = kmalloc_good_size(needed_capacity * sizeof(T)) / sizeof(T);
         auto* new_buffer = (T*)kmalloc(new_capacity * sizeof(T));
         if (new_buffer == nullptr)
             return false;
diff --git a/AK/kmalloc.h b/AK/kmalloc.h
index bd5e413a373..8217fe63f18 100644
--- a/AK/kmalloc.h
+++ b/AK/kmalloc.h
@@ -8,6 +8,12 @@
 
 #ifndef __serenity__
 #    include <new>
+
+#    ifndef AK_OS_MACOS
+inline size_t malloc_good_size(size_t size) { return size; }
+#    else
+#        include <malloc/malloc.h>
+#    endif
 #endif
 
 #ifdef KERNEL
@@ -27,6 +33,7 @@
 
 #    define kcalloc calloc
 #    define kmalloc malloc
+#    define kmalloc_good_size malloc_good_size
 #    define kfree free
 #    define krealloc realloc
 
diff --git a/Kernel/Heap/kmalloc.cpp b/Kernel/Heap/kmalloc.cpp
index 1e96825f87e..c7759f4ad77 100644
--- a/Kernel/Heap/kmalloc.cpp
+++ b/Kernel/Heap/kmalloc.cpp
@@ -277,6 +277,11 @@ void* krealloc(void* ptr, size_t new_size)
     return g_kmalloc_global->m_heap.reallocate(ptr, new_size);
 }
 
+size_t kmalloc_good_size(size_t size)
+{
+    return size;
+}
+
 void* operator new(size_t size) noexcept
 {
     return kmalloc(size);
diff --git a/Kernel/Heap/kmalloc.h b/Kernel/Heap/kmalloc.h
index 6fdc974c32a..624758ea530 100644
--- a/Kernel/Heap/kmalloc.h
+++ b/Kernel/Heap/kmalloc.h
@@ -66,4 +66,6 @@ inline void kfree_aligned(void* ptr)
     kfree((u8*)ptr - ((const ptrdiff_t*)ptr)[-1]);
 }
 
+size_t kmalloc_good_size(size_t);
+
 void kmalloc_enable_expand();
diff --git a/Userland/Libraries/LibC/malloc.cpp b/Userland/Libraries/LibC/malloc.cpp
index c175c02daf7..43519cf296c 100644
--- a/Userland/Libraries/LibC/malloc.cpp
+++ b/Userland/Libraries/LibC/malloc.cpp
@@ -392,6 +392,13 @@ size_t malloc_size(void* ptr)
     return size;
 }
 
+size_t malloc_good_size(size_t size)
+{
+    size_t good_size;
+    allocator_for_size(size, good_size);
+    return good_size;
+}
+
 void* realloc(void* ptr, size_t size)
 {
     if (!ptr)
diff --git a/Userland/Libraries/LibC/stdlib.h b/Userland/Libraries/LibC/stdlib.h
index 480e570cc74..c63e7eebc5f 100644
--- a/Userland/Libraries/LibC/stdlib.h
+++ b/Userland/Libraries/LibC/stdlib.h
@@ -21,6 +21,7 @@ __BEGIN_DECLS
 __attribute__((malloc)) __attribute__((alloc_size(1))) void* malloc(size_t);
 __attribute__((malloc)) __attribute__((alloc_size(1, 2))) void* calloc(size_t nmemb, size_t);
 size_t malloc_size(void*);
+size_t malloc_good_size(size_t);
 void serenity_dump_malloc_stats(void);
 void free(void*);
 __attribute__((alloc_size(2))) void* realloc(void* ptr, size_t);