diff --git a/Source/Core/Common/MemArenaAndroid.cpp b/Source/Core/Common/MemArenaAndroid.cpp
index 4a9e2f68b4..45b685274b 100644
--- a/Source/Core/Common/MemArenaAndroid.cpp
+++ b/Source/Core/Common/MemArenaAndroid.cpp
@@ -172,7 +172,9 @@ void LazyMemoryRegion::Clear()
 {
   ASSERT(m_memory);
 
-  mmap(m_memory, m_size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED, -1, 0);
+  void* new_memory = mmap(m_memory, m_size, PROT_READ | PROT_WRITE,
+                          MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED, -1, 0);
+  ASSERT(new_memory == m_memory);
 }
 
 void LazyMemoryRegion::Release()
diff --git a/Source/Core/Common/MemArenaUnix.cpp b/Source/Core/Common/MemArenaUnix.cpp
index 452c2c50c8..f962da755a 100644
--- a/Source/Core/Common/MemArenaUnix.cpp
+++ b/Source/Core/Common/MemArenaUnix.cpp
@@ -138,7 +138,9 @@ void LazyMemoryRegion::Clear()
 {
   ASSERT(m_memory);
 
-  mmap(m_memory, m_size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED, -1, 0);
+  void* new_memory = mmap(m_memory, m_size, PROT_READ | PROT_WRITE,
+                          MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED, -1, 0);
+  ASSERT(new_memory == m_memory);
 }
 
 void LazyMemoryRegion::Release()