diff --git a/src/Mem_unix.cpp b/src/Mem_unix.cpp
index 6deb2de6..97555cdb 100644
--- a/src/Mem_unix.cpp
+++ b/src/Mem_unix.cpp
@@ -66,9 +66,9 @@ bool Mem::allocate(const Options* options)
     m_flags |= HugepagesAvailable;
 
 #   if defined(__APPLE__)
-    m_memory = static_cast<uint8_t*>(mmap(0, size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON, VM_FLAGS_SUPERPAGE_SIZE_2MB, 0));
+    m_memory = static_cast<uint8_t*>(mmap(0, m_memorySize, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON, VM_FLAGS_SUPERPAGE_SIZE_2MB, 0));
 #   elif defined(__FreeBSD__)
-    m_memory = static_cast<uint8_t*>(mmap(0, size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS | MAP_ALIGNED_SUPER | MAP_PREFAULT_READ, -1, 0));
+    m_memory = static_cast<uint8_t*>(mmap(0, m_memorySize, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS | MAP_ALIGNED_SUPER | MAP_PREFAULT_READ, -1, 0));
 #   else
     m_memory = static_cast<uint8_t*>(mmap(0, m_memorySize, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB | MAP_POPULATE, 0, 0));
 #   endif