diff --git a/src/FDM/YASim/Turbulence.cpp b/src/FDM/YASim/Turbulence.cpp
index da9741f7e..4a6183680 100644
--- a/src/FDM/YASim/Turbulence.cpp
+++ b/src/FDM/YASim/Turbulence.cpp
@@ -138,8 +138,8 @@ void Turbulence::getTurbulence(double* loc, float alt, float* up,
     double b = (loc[1] + _off[1]) + _timeOff;
     a -= _sz * Math::floor(a * (1.0/_sz));
     b -= _sz * Math::floor(b * (1.0/_sz));
-    int x = (int)Math::floor(a);
-    int y = (int)Math::floor(b);
+    int x = ((int)Math::floor(a))&(_sz-1);
+    int y = ((int)Math::floor(b))&(_sz-1);
 
     // Convert to fractional interpolation factors
     a -= x;
diff --git a/src/FDM/YASim/YASim.cxx b/src/FDM/YASim/YASim.cxx
index 27fcbff6d..165a4b4aa 100644
--- a/src/FDM/YASim/YASim.cxx
+++ b/src/FDM/YASim/YASim.cxx
@@ -54,6 +54,11 @@ YASim::YASim(double dt)
     _fdm->getAirplane()->getModel()->getIntegrator()->setInterval(_dt);
 }
 
+YASim::~YASim()
+{
+    delete _fdm;
+}
+
 void YASim::report()
 {
     Airplane* a = _fdm->getAirplane();
diff --git a/src/FDM/YASim/YASim.hxx b/src/FDM/YASim/YASim.hxx
index 00771fd04..86e9e36b3 100644
--- a/src/FDM/YASim/YASim.hxx
+++ b/src/FDM/YASim/YASim.hxx
@@ -8,6 +8,7 @@ namespace yasim { class FGFDM; };
 class YASim : public FGInterface {
 public:
     YASim(double dt);
+    ~YASim();
 
     // Load externally set stuff into the FDM
     virtual void init();