diff --git a/lib/std/core/allocators/libc_allocator.c3 b/lib/std/core/allocators/libc_allocator.c3
index 4b59e5c5e..9967602f2 100644
--- a/lib/std/core/allocators/libc_allocator.c3
+++ b/lib/std/core/allocators/libc_allocator.c3
@@ -75,7 +75,7 @@ fn void*? LibcAllocator.resize(&self, void* old_ptr, usz new_bytes, usz alignmen
 		return mem::OUT_OF_MEMORY~;
 	}
 	// Now it is safe to copy the full range of data.
-	mem::copy(aligned_ptr, old_ptr, new_bytes, mem::DEFAULT_MEM_ALIGNMENT, mem::DEFAULT_MEM_ALIGNMENT);
+	mem::copy(aligned_ptr, new_ptr, new_bytes, mem::DEFAULT_MEM_ALIGNMENT, mem::DEFAULT_MEM_ALIGNMENT);
 	return aligned_ptr;
 
 }