diff --git a/include/clasp/core/mpPackage.fwd.h b/include/clasp/core/mpPackage.fwd.h
index cfaedadb7b..f46c7b35cf 100644
--- a/include/clasp/core/mpPackage.fwd.h
+++ b/include/clasp/core/mpPackage.fwd.h
@@ -354,6 +354,7 @@ struct Mutex {
     }
     return pthread_mutex_trylock(&this->_Mutex) == 0;
   };
+  bool try_lock() { return lock(false); } // for C++ Lockable
   void unlock() {
 #ifdef DEBUG_THREADS
     debug_mutex_unlock(this);
@@ -372,13 +373,24 @@ struct SharedMutex {
   size_t _b;
   SharedMutex(uint64_t nameword) : _r(nameword,false), _g(nameword,false), _b(0) {};
     // shared access
-  void shared_lock() {
+  void lock_shared() {
     this->_r.lock(true);
     ++this->_b;
     if (this->_b==256) this->_g.lock(true);
     this->_r.unlock();
   }
-  void shared_unlock() {
+  bool try_lock_shared() {
+    if (this->_r.try_lock()) {
+      if (this->_b>=255) {
+        this->_r.unlock();
+        return false;
+      } else {
+        ++this->_b;
+        return true;
+      }
+    } else return false;
+  }
+  void unlock_shared() {
     this->_r.lock(true);
     --this->_b;
     if (this->_b==0) this->_g.unlock();
@@ -397,9 +409,6 @@ struct SharedMutex : public sf::contention_free_shared_mutex<> {
   SharedMutex(){};
   uint64_t _r;
   SharedMutex(uint64_t nameword) : _r(nameword){};
-  // shared access
-  void shared_lock() { this->lock_shared(); }
-  void shared_unlock() { this->unlock_shared(); }
 };
 #endif
 
@@ -423,8 +432,8 @@ class UpgradableSharedMutex {
   UpgradableSharedMutex(uint64_t nameword, uint maxReaders = 64, uint64_t writenameword = 0)
       : mReadMutex(nameword), mWriteMutex(writenameword ? writenameword : nameword), mReadsBlocked(false), mMaxReaders(maxReaders),
         mReaders(0){};
-  void readLock() {
-    while (1) {
+  void lock_shared() {
+    while (true) {
       mReadMutex._value.lock();
       if ((!mReadsBlocked) && (mReaders < mMaxReaders)) {
         mReaders++;
@@ -436,7 +445,19 @@ class UpgradableSharedMutex {
     }
     assert(0);
   };
-  void readUnlock() {
+  bool try_lock_shared() {
+    if (mReadMutex._value.try_lock()) {
+      if ((!mReadsBlocked) && (mReaders < mMaxReaders)) {
+        mReaders++;
+        mReadMutex._value.unlock();
+        return true;
+      } else {
+        mReadMutex._value.unlock();
+        return false;
+      }
+    } else return false;
+  }
+  void unlock_shared() {
     mReadMutex._value.lock();
     assert(mReaders);
     mReaders--;
@@ -447,19 +468,19 @@ class UpgradableSharedMutex {
     Be careful though!!!! If two threads try to upgrade at the same time
     there will be a deadlock unless they do it in a loop using withTryLock(true).
    */
-  bool writeTryLock(bool upgrade = false) {
+  bool try_lock(bool upgrade = false) {
     if (!mWriteMutex._value.lock(false))
       return false;
     waitReaders(upgrade ? 1 : 0);
     return true;
   }
-  void writeLock(bool upgrade = false) {
+  void lock(bool upgrade = false) {
     mWriteMutex._value.lock();
     waitReaders(upgrade ? 1 : 0);
   }
   /*! Pass true releaseReadLock if when you release the write lock it also
      releases the read lock */
-  void writeUnlock(bool releaseReadLock = false) {
+  void unlock(bool releaseReadLock = false) {
     mReadMutex._value.lock();
     if (releaseReadLock) {
       assert(mReaders <= 1);
diff --git a/include/clasp/core/mpPackage.h b/include/clasp/core/mpPackage.h
index d1a0ceb68d..b482ec8c26 100644
--- a/include/clasp/core/mpPackage.h
+++ b/include/clasp/core/mpPackage.h
@@ -227,14 +227,13 @@ class SharedMutex_O : public core::CxxObject_O {
   SharedMutex_O(core::T_sp readName, core::T_sp writeName = nil<core::T_O>())
       : _Name(readName), _Owner(nil<T_O>()),
         _SharedMutex(lisp_nameword(readName), 256, writeName.nilp() ? lisp_nameword(readName) : lisp_nameword(writeName)){};
-  void write_lock(bool upgrade = false) { this->_SharedMutex.writeLock(upgrade); };
-  bool write_try_lock(bool upgrade = false) { return this->_SharedMutex.writeTryLock(upgrade); };
-  void write_unlock(bool release_read_lock = false) { this->_SharedMutex.writeUnlock(release_read_lock); };
-
-  void read_lock() { this->_SharedMutex.readLock(); };
-  void read_unlock() { this->_SharedMutex.readUnlock(); };
-  void shared_lock() { this->_SharedMutex.readLock(); };
-  void shared_unlock() { this->_SharedMutex.readUnlock(); };
+  void lock(bool upgrade = false) { this->_SharedMutex.lock(upgrade); };
+  bool try_lock(bool upgrade = false) { return this->_SharedMutex.try_lock(upgrade); };
+  void unlock(bool release_read_lock = false) { this->_SharedMutex.unlock(release_read_lock); };
+
+  void lock_shared() { this->_SharedMutex.lock_shared(); };
+  bool try_lock_shared() { return this->_SharedMutex.try_lock_shared(); }
+  void unlock_shared() { this->_SharedMutex.unlock_shared(); };
   void setLockNames(core::SimpleBaseString_sp readLockName, core::SimpleBaseString_sp writeLockName);
   string __repr__() const override;
 
diff --git a/src/core/hashTable.cc b/src/core/hashTable.cc
index 366fb6f8e7..4ee39679fc 100644
--- a/src/core/hashTable.cc
+++ b/src/core/hashTable.cc
@@ -160,12 +160,12 @@ struct HashTableReadLock {
   const HashTable_O* _hashTable;
   HashTableReadLock(const HashTable_O* ht) : _hashTable(ht) {
     if (this->_hashTable->_Mutex) {
-      this->_hashTable->_Mutex->shared_lock();
+      this->_hashTable->_Mutex->lock_shared();
     }
   }
   ~HashTableReadLock() {
     if (this->_hashTable->_Mutex) {
-      this->_hashTable->_Mutex->shared_unlock();
+      this->_hashTable->_Mutex->unlock_shared();
     }
   }
 };
@@ -173,12 +173,12 @@ struct HashTableWriteLock {
   const HashTable_O* _hashTable;
   HashTableWriteLock(const HashTable_O* ht, bool upgrade = false) : _hashTable(ht) {
     if (this->_hashTable->_Mutex) {
-      this->_hashTable->_Mutex->write_lock(upgrade);
+      this->_hashTable->_Mutex->lock(upgrade);
     }
   }
   ~HashTableWriteLock() {
     if (this->_hashTable->_Mutex) {
-      this->_hashTable->_Mutex->write_unlock();
+      this->_hashTable->_Mutex->unlock();
     }
   }
 };
diff --git a/src/core/mpPackage.cc b/src/core/mpPackage.cc
index 411d60f8c7..94ad1ea466 100644
--- a/src/core/mpPackage.cc
+++ b/src/core/mpPackage.cc
@@ -224,29 +224,29 @@ CL_LAMBDA(mutex &optional (upgrade nil));
 CL_DOCSTRING(
     R"dx(Obtain the write lock for this mutex. upgradep should be true if and only if this thread currently holds the shared lock for the same mutex.)dx");
 DOCGROUP(clasp);
-CL_DEFUN void mp__write_lock(SharedMutex_sp m, bool upgrade) { m->write_lock(upgrade); }
+CL_DEFUN void mp__write_lock(SharedMutex_sp m, bool upgrade) { m->lock(upgrade); }
 
 CL_LAMBDA(mutex &optional (upgrade nil));
 CL_DOCSTRING(
     R"dx(Try to obtain the write lock for this mutex. If it cannot be obtained immediately, return false. Otherwise, return true.)dx");
 DOCGROUP(clasp);
-CL_DEFUN bool mp__write_try_lock(SharedMutex_sp m, bool upgrade) { return m->write_try_lock(upgrade); }
+CL_DEFUN bool mp__write_try_lock(SharedMutex_sp m, bool upgrade) { return m->try_lock(upgrade); }
 
 CL_LAMBDA(mutex &optional (release_read_lock nil));
 CL_DOCSTRING(
     R"dx(Release the write lock. If releasep is true and the current thread holds the shared lock, it is released as well.)dx");
 DOCGROUP(clasp);
-CL_DEFUN void mp__write_unlock(SharedMutex_sp m, bool release_read_lock) { m->write_unlock(release_read_lock); }
+CL_DEFUN void mp__write_unlock(SharedMutex_sp m, bool release_read_lock) { m->unlock(release_read_lock); }
 
 CL_LAMBDA(mutex);
 CL_DOCSTRING(R"dx(Obtain the shared lock for this mutex.)dx");
 DOCGROUP(clasp);
-CL_DEFUN void mp__shared_lock(SharedMutex_sp m) { m->read_lock(); }
+CL_DEFUN void mp__shared_lock(SharedMutex_sp m) { m->lock_shared(); }
 
 CL_LAMBDA(mutex);
 CL_DOCSTRING(R"dx(Release the shared lock for this mutex.)dx");
 DOCGROUP(clasp);
-CL_DEFUN void mp__shared_unlock(SharedMutex_sp m) { m->read_unlock(); }
+CL_DEFUN void mp__shared_unlock(SharedMutex_sp m) { m->unlock_shared(); }
 
 void SharedMutex_O::setLockNames(core::SimpleBaseString_sp readLockName, core::SimpleBaseString_sp writeLockName) {
   this->_SharedMutex.mReadMutex._value._NameWord = lisp_nameword(readLockName);
diff --git a/src/gctools/gcweak.cc b/src/gctools/gcweak.cc
index 36ea7c145a..fca1f72fd5 100644
--- a/src/gctools/gcweak.cc
+++ b/src/gctools/gcweak.cc
@@ -45,12 +45,12 @@ struct WeakKeyHashTableReadLock {
   const WeakKeyHashTable* _hashTable;
   WeakKeyHashTableReadLock(const WeakKeyHashTable* ht) : _hashTable(ht) {
     if (this->_hashTable->_Mutex) {
-      this->_hashTable->_Mutex->shared_lock();
+      this->_hashTable->_Mutex->lock_shared();
     }
   }
   ~WeakKeyHashTableReadLock() {
     if (this->_hashTable->_Mutex) {
-      this->_hashTable->_Mutex->shared_unlock();
+      this->_hashTable->_Mutex->unlock_shared();
     }
   }
 };
@@ -58,12 +58,12 @@ struct WeakKeyHashTableWriteLock {
   const WeakKeyHashTable* _hashTable;
   WeakKeyHashTableWriteLock(const WeakKeyHashTable* ht, bool upgrade = false) : _hashTable(ht) {
     if (this->_hashTable->_Mutex) {
-      this->_hashTable->_Mutex->write_lock(upgrade);
+      this->_hashTable->_Mutex->lock(upgrade);
     }
   }
   ~WeakKeyHashTableWriteLock() {
     if (this->_hashTable->_Mutex) {
-      this->_hashTable->_Mutex->write_unlock();
+      this->_hashTable->_Mutex->unlock();
     }
   }
 };