diff --git a/mozglue/linker/ElfLoader.cpp b/mozglue/linker/ElfLoader.cpp
index a9a6c6a125b..955eacb42dc 100644
--- a/mozglue/linker/ElfLoader.cpp
+++ b/mozglue/linker/ElfLoader.cpp
@@ -208,7 +208,14 @@ LibHandle::MappableMMap(void *addr, size_t length, off_t offset) const
 {
   MOZ_ASSERT(mappable == NULL, "MappableMMap must be called after"
                                " GetMappableLength");
-  return mappable->mmap(addr, length, PROT_READ, MAP_PRIVATE, offset);
+  void* mapped = mappable->mmap(addr, length, PROT_READ, MAP_PRIVATE, offset);
+  if (mapped != MAP_FAILED) {
+    /* Ensure the availability of all pages within the mapping */
+    for (size_t off = 0; off < length; off += PAGE_SIZE) {
+      mappable->ensure(reinterpret_cast<char *>(mapped) + off);
+    }
+  }
+  return mapped;
 }
 
 void