diff --git a/src/runtime/Memory.cpp b/src/runtime/Memory.cpp
index 0fced6104..9903d48a2 100644
--- a/src/runtime/Memory.cpp
+++ b/src/runtime/Memory.cpp
@@ -21,6 +21,11 @@
 #include "runtime/Instance.h"
 #include "runtime/Module.h"
 
+#if defined(OS_POSIX)
+#define WALRUS_USE_MMAP
+#include <sys/mman.h>
+#endif
+
 namespace Walrus {
 
 Memory* Memory::createMemory(Store* store, uint64_t initialSizeInByte, uint64_t maximumSizeInByte)
@@ -32,30 +37,85 @@ Memory* Memory::createMemory(Store* store, uint64_t initialSizeInByte, uint64_t
 
 Memory::Memory(uint64_t initialSizeInByte, uint64_t maximumSizeInByte)
     : m_sizeInByte(initialSizeInByte)
+    , m_reservedSizeInByte(0)
     , m_maximumSizeInByte(maximumSizeInByte)
-    , m_buffer(reinterpret_cast<uint8_t*>(calloc(1, initialSizeInByte)))
+    , m_buffer(nullptr)
 {
+    RELEASE_ASSERT(initialSizeInByte <= std::numeric_limits<size_t>::max());
+#if defined(WALRUS_USE_MMAP)
+    if (m_maximumSizeInByte) {
+#ifndef WALRUS_32_MEMORY_INITIAL_MMAP_RESERVED_ADDRESS_SIZE
+#define WALRUS_32_MEMORY_INITIAL_MMAP_RESERVED_ADDRESS_SIZE (1024 * 1024 * 64)
+#endif
+#ifndef WALRUS_64_MEMORY_INITIAL_MMAP_RESERVED_ADDRESS_SIZE
+#define WALRUS_64_MEMORY_INITIAL_MMAP_RESERVED_ADDRESS_SIZE (1024 * 1024 * 512)
+#endif
+        uint64_t initialReservedSize =
+#if defined(WALRUS_32)
+            WALRUS_32_MEMORY_INITIAL_MMAP_RESERVED_ADDRESS_SIZE;
+#else
+            WALRUS_64_MEMORY_INITIAL_MMAP_RESERVED_ADDRESS_SIZE;
+#endif
+        m_reservedSizeInByte = std::min(initialReservedSize, m_maximumSizeInByte);
+        m_buffer = reinterpret_cast<uint8_t*>(mmap(NULL, m_reservedSizeInByte, PROT_NONE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0));
+        RELEASE_ASSERT(MAP_FAILED != m_buffer);
+        mprotect(m_buffer, initialSizeInByte, (PROT_READ | PROT_WRITE));
+    } else {
+        m_reservedSizeInByte = 0;
+        m_buffer = nullptr;
+    }
+#else
+    m_buffer = reinterpret_cast<uint8_t*>(calloc(1, initialSizeInByte));
+    m_reservedSizeInByte = initialSizeInByte;
     RELEASE_ASSERT(m_buffer);
+#endif
 }
 
 Memory::~Memory()
 {
+#if defined(WALRUS_USE_MMAP)
+    if (m_buffer) {
+        munmap(m_buffer, m_reservedSizeInByte);
+    }
+#else
     ASSERT(!!m_buffer);
     free(m_buffer);
+#endif
 }
 
 bool Memory::grow(uint64_t growSizeInByte)
 {
     uint64_t newSizeInByte = growSizeInByte + m_sizeInByte;
     if (newSizeInByte > m_sizeInByte && newSizeInByte <= m_maximumSizeInByte) {
-        uint8_t* newBuffer = reinterpret_cast<uint8_t*>(calloc(1, newSizeInByte));
-        if (newBuffer) {
+#if defined(WALRUS_USE_MMAP)
+        if (newSizeInByte <= m_reservedSizeInByte) {
+            mprotect(m_buffer + m_sizeInByte, growSizeInByte, (PROT_READ | PROT_WRITE));
+            m_sizeInByte = newSizeInByte;
+        } else {
+            auto newReservedSizeInByte = std::min(newSizeInByte * 2, m_maximumSizeInByte);
+            auto newBuffer = reinterpret_cast<uint8_t*>(mmap(NULL, newReservedSizeInByte, PROT_NONE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0));
+            if (MAP_FAILED == newBuffer) {
+                return false;
+            }
+            mprotect(newBuffer, newSizeInByte, (PROT_READ | PROT_WRITE));
             memcpy(newBuffer, m_buffer, m_sizeInByte);
-            free(m_buffer);
+            munmap(m_buffer, m_reservedSizeInByte);
             m_buffer = newBuffer;
             m_sizeInByte = newSizeInByte;
-            return true;
+            m_reservedSizeInByte = newReservedSizeInByte;
         }
+#else
+        uint8_t* newBuffer = reinterpret_cast<uint8_t*>(calloc(1, newSizeInByte));
+        if (newBuffer == nullptr || newSizeInByte >= std::numeric_limits<size_t>::max()) {
+            return false;
+        }
+        m_reservedSizeInByte = newSizeInByte;
+        memcpy(newBuffer, m_buffer, m_sizeInByte);
+        free(m_buffer);
+        m_buffer = newBuffer;
+        m_sizeInByte = newSizeInByte;
+#endif
+        return true;
     } else if (newSizeInByte == m_sizeInByte) {
         return true;
     }
diff --git a/src/runtime/Memory.h b/src/runtime/Memory.h
index 938a00c4b..34937d025 100644
--- a/src/runtime/Memory.h
+++ b/src/runtime/Memory.h
@@ -133,6 +133,7 @@ class Memory : public Extern {
     inline void fillMemory(uint32_t start, uint8_t value, uint32_t size);
 
     uint64_t m_sizeInByte;
+    uint64_t m_reservedSizeInByte;
     uint64_t m_maximumSizeInByte;
     uint8_t* m_buffer;
 };
diff --git a/test/basic/memory.wast b/test/basic/memory.wast
index c9b3e2a91..1608dc6b0 100644
--- a/test/basic/memory.wast
+++ b/test/basic/memory.wast
@@ -17,4 +17,5 @@
   (memory 0)
   (func (export "grow") (param i32) (result i32) (memory.grow (local.get 0)))
 )
-(assert_return (invoke "grow" (i32.const 0x10000)) (i32.const 0))
+(assert_return (invoke "grow" (i32.const 0x1000)) (i32.const 0))
+(assert_return (invoke "grow" (i32.const 0x10000)) (i32.const -1))
diff --git a/third_party/wabt/src/walrus/binary-reader-walrus.cc b/third_party/wabt/src/walrus/binary-reader-walrus.cc
index 39475168b..cc6584da6 100644
--- a/third_party/wabt/src/walrus/binary-reader-walrus.cc
+++ b/third_party/wabt/src/walrus/binary-reader-walrus.cc
@@ -246,7 +246,8 @@ class BinaryReaderDelegateWalrus: public BinaryReaderDelegate {
     }
     Result OnImportMemory(Index import_index, nonstd::string_view module_name, nonstd::string_view field_name, Index memory_index, const Limits *page_limits) override {
         CHECK_RESULT(m_validator.OnMemory(GetLocation(), *page_limits));
-        m_externalDelegate->OnImportMemory(import_index, std::string(module_name), std::string(field_name), memory_index, page_limits->initial, page_limits->has_max ? page_limits->max : (page_limits->is_64? WABT_MAX_PAGES64 : WABT_MAX_PAGES32));
+        m_externalDelegate->OnImportMemory(import_index, std::string(module_name), std::string(field_name), memory_index, page_limits->initial,
+            page_limits->has_max ? page_limits->max : (page_limits->is_64? (WABT_MAX_PAGES64 - 1) : (WABT_MAX_PAGES32 - 1)));
         return Result::Ok;
     }
     Result OnImportGlobal(Index import_index, nonstd::string_view module_name, nonstd::string_view field_name, Index global_index, Type type, bool mutable_) override {
@@ -308,7 +309,8 @@ class BinaryReaderDelegateWalrus: public BinaryReaderDelegate {
     }
     Result OnMemory(Index index, const Limits *limits) override {
         CHECK_RESULT(m_validator.OnMemory(GetLocation(), *limits));
-        m_externalDelegate->OnMemory(index, limits->initial, limits->has_max ? limits->max : (limits->is_64? WABT_MAX_PAGES64 : WABT_MAX_PAGES32));
+        m_externalDelegate->OnMemory(index, limits->initial,
+            limits->has_max ? limits->max : (limits->is_64 ? (WABT_MAX_PAGES64 - 1) : (WABT_MAX_PAGES32 - 1)));
         return Result::Ok;
     }
     Result EndMemorySection() override {