diff --git a/gtsam/base/debug.cpp b/gtsam/base/debug.cpp
index dbea53c7c..592b42d15 100644
--- a/gtsam/base/debug.cpp
+++ b/gtsam/base/debug.cpp
@@ -19,23 +19,31 @@
 #include <gtsam/base/debug.h>
 #include <gtsam/config.h> // for GTSAM_USE_TBB
 
+#ifdef GTSAM_USE_TBB
 #include <mutex> // std::mutex, std::unique_lock
+#endif
 
 namespace gtsam {
 
 GTSAM_EXPORT FastMap<std::string, ValueWithDefault<bool, false> > debugFlags;
 
+#ifdef GTSAM_USE_TBB
 std::mutex debugFlagsMutex;
+#endif
 
 /* ************************************************************************* */
 bool guardedIsDebug(const std::string& s) {
+#ifdef GTSAM_USE_TBB
   std::unique_lock<std::mutex> lock(debugFlagsMutex);
+#endif
   return gtsam::debugFlags[s];
 }
 
 /* ************************************************************************* */
 void guardedSetDebug(const std::string& s, const bool v) {
+#ifdef GTSAM_USE_TBB
   std::unique_lock<std::mutex> lock(debugFlagsMutex);
+#endif
   gtsam::debugFlags[s] = v;
 }
 
diff --git a/gtsam/geometry/Unit3.cpp b/gtsam/geometry/Unit3.cpp
index 655b94fc3..f33e08a83 100644
--- a/gtsam/geometry/Unit3.cpp
+++ b/gtsam/geometry/Unit3.cpp
@@ -80,10 +80,12 @@ static Point3 CalculateBestAxis(const Point3& n) {
 
 /* ************************************************************************* */
 const Matrix32& Unit3::basis(OptionalJacobian<6, 2> H) const {
+#ifdef GTSAM_USE_TBB
   // NOTE(hayk): At some point it seemed like this reproducably resulted in
   // deadlock. However, I don't know why and I can no longer reproduce it.
   // It either was a red herring or there is still a latent bug left to debug.
   std::unique_lock<std::mutex> lock(B_mutex_);
+#endif
 
   const bool cachedBasis = static_cast<bool>(B_);
   const bool cachedJacobian = static_cast<bool>(H_B_);
diff --git a/gtsam/geometry/Unit3.h b/gtsam/geometry/Unit3.h
index 0a43ce59b..a4043be85 100644
--- a/gtsam/geometry/Unit3.h
+++ b/gtsam/geometry/Unit3.h
@@ -32,7 +32,9 @@
 
 #include <string>
 
+#ifdef GTSAM_USE_TBB
 #include <mutex> // std::mutex
+#endif
 
 namespace gtsam {
 
@@ -45,7 +47,9 @@ private:
   mutable boost::optional<Matrix32> B_; ///< Cached basis
   mutable boost::optional<Matrix62> H_B_; ///< Cached basis derivative
 
+#ifdef GTSAM_USE_TBB
   mutable std::mutex B_mutex_; ///< Mutex to protect the cached basis.
+#endif
 
 public: