diff --git a/Keymaster.h b/Keymaster.h
index fabe0f4..42a2b5d 100644
--- a/Keymaster.h
+++ b/Keymaster.h
@@ -46,8 +46,8 @@ class KeymasterOperation {
     ~KeymasterOperation();
     // Is this instance valid? This is false if creation fails, and becomes
     // false on finish or if an update fails.
-    explicit operator bool() { return mError == km::ErrorCode::OK; }
-    km::ErrorCode errorCode() { return mError; }
+    explicit operator bool() const { return mError == km::ErrorCode::OK; }
+    km::ErrorCode errorCode() const { return mError; }
     // Call "update" repeatedly until all of the input is consumed, and
     // concatenate the output. Return true on success.
     template <class TI, class TO>
diff --git a/VolumeManager.cpp b/VolumeManager.cpp
index bcc6570..d113cf9 100644
--- a/VolumeManager.cpp
+++ b/VolumeManager.cpp
@@ -327,7 +327,8 @@ std::shared_ptr<android::vold::VolumeBase> VolumeManager::findVolume(const std::
     return nullptr;
 }
 
-void VolumeManager::listVolumes(android::vold::VolumeBase::Type type, std::list<std::string>& list) {
+void VolumeManager::listVolumes(android::vold::VolumeBase::Type type,
+                                std::list<std::string>& list) const {
     list.clear();
     for (const auto& disk : mDisks) {
         disk->listVolumes(type, list);
diff --git a/VolumeManager.h b/VolumeManager.h
index 01a81d1..3a7bae4 100644
--- a/VolumeManager.h
+++ b/VolumeManager.h
@@ -52,7 +52,7 @@ class VolumeManager {
     std::mutex& getCryptLock() { return mCryptLock; }
 
     void setListener(android::sp<android::os::IVoldListener> listener) { mListener = listener; }
-    android::sp<android::os::IVoldListener> getListener() { return mListener; }
+    android::sp<android::os::IVoldListener> getListener() const { return mListener; }
 
     int start();
     int stop();
@@ -68,8 +68,8 @@ class VolumeManager {
             return !fnmatch(mSysPattern.c_str(), sysPath.c_str(), 0);
         }
 
-        const std::string& getNickname() { return mNickname; }
-        int getFlags() { return mFlags; }
+        const std::string& getNickname() const { return mNickname; }
+        int getFlags() const { return mFlags; }
 
       private:
         std::string mSysPattern;
@@ -82,7 +82,7 @@ class VolumeManager {
     std::shared_ptr<android::vold::Disk> findDisk(const std::string& id);
     std::shared_ptr<android::vold::VolumeBase> findVolume(const std::string& id);
 
-    void listVolumes(android::vold::VolumeBase::Type type, std::list<std::string>& list);
+    void listVolumes(android::vold::VolumeBase::Type type, std::list<std::string>& list) const;
 
     int forgetPartition(const std::string& partGuid, const std::string& fsUuid);
 
diff --git a/model/Disk.cpp b/model/Disk.cpp
index 1568ba4..b66c336 100644
--- a/model/Disk.cpp
+++ b/model/Disk.cpp
@@ -153,7 +153,7 @@ std::shared_ptr<VolumeBase> Disk::findVolume(const std::string& id) {
     return nullptr;
 }
 
-void Disk::listVolumes(VolumeBase::Type type, std::list<std::string>& list) {
+void Disk::listVolumes(VolumeBase::Type type, std::list<std::string>& list) const {
     for (const auto& vol : mVolumes) {
         if (vol->getType() == type) {
             list.push_back(vol->getId());
diff --git a/model/Disk.h b/model/Disk.h
index 3140144..889e906 100644
--- a/model/Disk.h
+++ b/model/Disk.h
@@ -54,18 +54,18 @@ class Disk {
         kEmmc = 1 << 4,
     };
 
-    const std::string& getId() { return mId; }
-    const std::string& getEventPath() { return mEventPath; }
-    const std::string& getSysPath() { return mSysPath; }
-    const std::string& getDevPath() { return mDevPath; }
-    dev_t getDevice() { return mDevice; }
-    uint64_t getSize() { return mSize; }
-    const std::string& getLabel() { return mLabel; }
-    int getFlags() { return mFlags; }
+    const std::string& getId() const { return mId; }
+    const std::string& getEventPath() const { return mEventPath; }
+    const std::string& getSysPath() const { return mSysPath; }
+    const std::string& getDevPath() const { return mDevPath; }
+    dev_t getDevice() const { return mDevice; }
+    uint64_t getSize() const { return mSize; }
+    const std::string& getLabel() const { return mLabel; }
+    int getFlags() const { return mFlags; }
 
     std::shared_ptr<VolumeBase> findVolume(const std::string& id);
 
-    void listVolumes(VolumeBase::Type type, std::list<std::string>& list);
+    void listVolumes(VolumeBase::Type type, std::list<std::string>& list) const;
 
     status_t create();
     status_t destroy();
diff --git a/model/PrivateVolume.h b/model/PrivateVolume.h
index 85aa4dc..cb8e75d 100644
--- a/model/PrivateVolume.h
+++ b/model/PrivateVolume.h
@@ -39,9 +39,9 @@ class PrivateVolume : public VolumeBase {
   public:
     PrivateVolume(dev_t device, const std::string& keyRaw);
     virtual ~PrivateVolume();
-    const std::string& getFsType() { return mFsType; };
-    const std::string& getRawDevPath() { return mRawDevPath; };
-    const std::string& getRawDmDevPath() { return mDmDevPath; };
+    const std::string& getFsType() const { return mFsType; };
+    const std::string& getRawDevPath() const { return mRawDevPath; };
+    const std::string& getRawDmDevPath() const { return mDmDevPath; };
 
   protected:
     status_t doCreate() override;
diff --git a/model/VolumeBase.cpp b/model/VolumeBase.cpp
index 29bc32c..a9c7fa3 100644
--- a/model/VolumeBase.cpp
+++ b/model/VolumeBase.cpp
@@ -153,7 +153,7 @@ status_t VolumeBase::setLabel(const std::string& label) {
     return OK;
 }
 
-android::sp<android::os::IVoldListener> VolumeBase::getListener() {
+android::sp<android::os::IVoldListener> VolumeBase::getListener() const {
     if (mSilent) {
         return nullptr;
     } else {
diff --git a/model/VolumeBase.h b/model/VolumeBase.h
index ea187bd..e6c47f0 100644
--- a/model/VolumeBase.h
+++ b/model/VolumeBase.h
@@ -78,16 +78,16 @@ class VolumeBase {
         kBadRemoval,
     };
 
-    const std::string& getId() { return mId; }
-    const std::string& getDiskId() { return mDiskId; }
-    const std::string& getPartGuid() { return mPartGuid; }
-    Type getType() { return mType; }
-    int getMountFlags() { return mMountFlags; }
-    userid_t getMountUserId() { return mMountUserId; }
-    State getState() { return mState; }
-    const std::string& getPath() { return mPath; }
-    const std::string& getInternalPath() { return mInternalPath; }
-    const std::string& getLabel() { return mLabel; }
+    const std::string& getId() const { return mId; }
+    const std::string& getDiskId() const { return mDiskId; }
+    const std::string& getPartGuid() const { return mPartGuid; }
+    Type getType() const { return mType; }
+    int getMountFlags() const { return mMountFlags; }
+    userid_t getMountUserId() const { return mMountUserId; }
+    State getState() const { return mState; }
+    const std::string& getPath() const { return mPath; }
+    const std::string& getInternalPath() const { return mInternalPath; }
+    const std::string& getLabel() const { return mLabel; }
 
     status_t setDiskId(const std::string& diskId);
     status_t setPartGuid(const std::string& partGuid);
@@ -124,7 +124,7 @@ class VolumeBase {
     status_t setInternalPath(const std::string& internalPath);
     status_t setLabel(const std::string& label);
 
-    android::sp<android::os::IVoldListener> getListener();
+    android::sp<android::os::IVoldListener> getListener() const;
 
   private:
     /* ID that uniquely references volume while alive */