diff --git a/include/GObservations.hpp b/include/GObservations.hpp
index c7f5185..6dd2cef 100644
--- a/include/GObservations.hpp
+++ b/include/GObservations.hpp
@@ -125,6 +125,7 @@ public:
     void                models(const std::string& filename);
     const GModels&      models(void) const;
     void                optimize(GOptimizer& opt);
+    void                errors(GOptimizer& opt);
     void                eval(void);
     double              logL(void) const;
     double              npred(void) const;
diff --git a/include/GOptimizer.hpp b/include/GOptimizer.hpp
index 892b964..73a236a 100644
--- a/include/GOptimizer.hpp
+++ b/include/GOptimizer.hpp
@@ -67,6 +67,7 @@ public:
     virtual GOptimizer* clone(void) const = 0;
     virtual std::string classname(void) const = 0;
     virtual void        optimize(GOptimizerFunction& fct, GOptimizerPars& pars) = 0;
+    virtual void        errors(GOptimizerFunction& fct, GOptimizerPars& pars) = 0;
     virtual double      value(void) const = 0;
     virtual int         status(void) const = 0;
     virtual int         iter(void) const = 0;
diff --git a/include/GOptimizerLM.hpp b/include/GOptimizerLM.hpp
index 09a86e7..c81ae92 100644
--- a/include/GOptimizerLM.hpp
+++ b/include/GOptimizerLM.hpp
@@ -66,6 +66,7 @@ public:
     virtual GOptimizerLM* clone(void) const;
     virtual std::string   classname(void) const;
     virtual void          optimize(GOptimizerFunction& fct, GOptimizerPars& pars);
+    void                      errors(GOptimizerFunction& fct, GOptimizerPars& pars);
     virtual double        value(void) const { return m_value; }   //!< @brief Return function value
     virtual int           status(void) const { return m_status; } //!< @brief Return optimization status
     virtual int           iter(void) const { return m_iter; }     //!< @brief Return number of iterations
@@ -94,7 +95,6 @@ protected:
     void   copy_members(const GOptimizerLM& opt);
     void   free_members(void);
     void   iteration(GOptimizerFunction& fct, GOptimizerPars& pars);
-    void   errors(GOptimizerFunction& fct, GOptimizerPars& pars);
     double step_size(const GVector& grad, const GOptimizerPars& pars);
 
     // Protected members
diff --git a/src/obs/GObservations.cpp b/src/obs/GObservations.cpp
index 54f1f93..245a19f 100644
--- a/src/obs/GObservations.cpp
+++ b/src/obs/GObservations.cpp
@@ -722,6 +722,27 @@ void GObservations::optimize(GOptimizer& opt)
 
 
 /***********************************************************************//**
+ * @brief Computes parameter errors using optimizer
+ *
+ * @param[in] opt Optimizer.
+ *
+ * Calculates the errors of the free parameters of the models by using
+ * the optimizer that has been provided by the @p opt argument.
+ ***************************************************************************/
+void GObservations::errors(GOptimizer& opt)
+{
+    // Extract optimizer parameter container from model container
+    GOptimizerPars pars = m_models.pars();
+
+    // Optimize model parameters
+    opt.errors(m_fct, pars);
+
+    // Return
+    return;
+}
+
+
+/***********************************************************************//**
  * @brief Evaluate function
  *
  * Evaluates the likelihood funtion at the actual set of parameters.
diff --git a/src/opt/GOptimizerLM.cpp b/src/opt/GOptimizerLM.cpp
index 0e362a9..2c87228 100644
--- a/src/opt/GOptimizerLM.cpp
+++ b/src/opt/GOptimizerLM.cpp
@@ -409,9 +409,6 @@ void GOptimizerLM::optimize(GOptimizerFunction& fct, GOptimizerPars& pars)
             }
 
         } // endfor: iterations
-
-        // Compute parameter uncertainties
-        errors(fct, pars);
         
         // Free now all temporarily frozen parameters so that the resulting
         // model has the same attributes as the initial model
@@ -432,7 +429,12 @@ void GOptimizerLM::optimize(GOptimizerFunction& fct, GOptimizerPars& pars)
 
     // ... otherwise just execute final step
     else {
-        errors(fct, pars);
+
+    	// Evaluate function
+        fct.eval(pars);
+
+        // Save function value
+        m_value = fct.value();
     }
 
     // Return