diff --git a/Checkpoint.cpp b/Checkpoint.cpp
index 362c823..a2db4bd 100644
--- a/Checkpoint.cpp
+++ b/Checkpoint.cpp
@@ -144,9 +144,15 @@
 namespace {
 
 volatile bool isCheckpointing = false;
+
+// Protects isCheckpointing and code that makes decisions based on status of
+// isCheckpointing
+std::mutex isCheckpointingLock;
 }
 
 Status cp_commitChanges() {
+    std::lock_guard<std::mutex> lock(isCheckpointingLock);
+
     if (!isCheckpointing) {
         return Status::ok();
     }
@@ -261,6 +267,7 @@
     std::string content;
     sp<IBootControl> module = IBootControl::getService();
 
+    std::lock_guard<std::mutex> lock(isCheckpointingLock);
     if (isCheckpointing) return isCheckpointing;
 
     if (module && module->isSlotMarkedSuccessful(module->getCurrentSlot()) == BoolResult::FALSE) {
@@ -330,6 +337,7 @@
 }  // namespace
 
 Status cp_prepareCheckpoint() {
+    std::lock_guard<std::mutex> lock(isCheckpointingLock);
     if (!isCheckpointing) {
         return Status::ok();
     }