diff --git a/js/src/jit/ProcessExecutableMemory.cpp b/js/src/jit/ProcessExecutableMemory.cpp
index 7c40d93c71..d9e7c28f66 100644
--- a/js/src/jit/ProcessExecutableMemory.cpp
+++ b/js/src/jit/ProcessExecutableMemory.cpp
@@ -287,8 +287,15 @@ ReserveProcessExecutableMemory(size_t bytes)
     // Note that randomAddr is just a hint: if the address is not available
     // mmap will pick a different address.
     void* randomAddr = ComputeRandomAllocationAddress();
+#ifdef PROT_MPROTECT
+    void* p = MozTaggedAnonymousMmap(randomAddr, bytes,
+                                     PROT_MPROTECT(PROT_EXEC | PROT_WRITE | PROT_READ),
+                                     MAP_PRIVATE | MAP_ANON,
+                                     -1, 0, "js-executable-memory");
+#else
     void* p = MozTaggedAnonymousMmap(randomAddr, bytes, PROT_NONE, MAP_PRIVATE | MAP_ANON,
                                      -1, 0, "js-executable-memory");
+#endif
     if (p == MAP_FAILED)
         return nullptr;
     return p;
@@ -315,7 +322,13 @@ ProtectionSettingToFlags(ProtectionSetting protection)
 static void
 CommitPages(void* addr, size_t bytes, ProtectionSetting protection)
 {
-    void* p = MozTaggedAnonymousMmap(addr, bytes, ProtectionSettingToFlags(protection),
+    void* p = MozTaggedAnonymousMmap(addr, bytes,
+#ifdef PROT_MPROTECT
+                                     ProtectionSettingToFlags(protection) |
+                                     PROT_MPROTECT(PROT_EXEC | PROT_WRITE | PROT_READ),
+#else
+                                     ProtectionSettingToFlags(protection),
+#endif
                                      MAP_FIXED | MAP_PRIVATE | MAP_ANON,
                                      -1, 0, "js-executable-memory");
     MOZ_RELEASE_ASSERT(addr == p);
diff --git a/js/src/vm/ArrayBufferObject.cpp b/js/src/vm/ArrayBufferObject.cpp
index 6ace034adb..06e31f208c 100644
--- a/js/src/vm/ArrayBufferObject.cpp
+++ b/js/src/vm/ArrayBufferObject.cpp
@@ -644,7 +644,12 @@ WasmArrayRawBuffer::Allocate(uint32_t numBytes, Maybe<uint32_t> maxSize)
         return nullptr;
     }
 # else  // XP_WIN
-    void* data = MozTaggedAnonymousMmap(nullptr, (size_t) mappedSizeWithHeader, PROT_NONE,
+    void* data = MozTaggedAnonymousMmap(nullptr, (size_t) mappedSizeWithHeader,
+#ifdef PROT_MPROTECT
+                                        PROT_MPROTECT(PROT_EXEC | PROT_WRITE | PROT_READ),
+#else
+                                        PROT_NONE,
+#endif
                                         MAP_PRIVATE | MAP_ANON, -1, 0, "wasm-reserved");
     if (data == MAP_FAILED)
         return nullptr;