diff --git a/src/Mod/Sketcher/App/SketchObject.cpp b/src/Mod/Sketcher/App/SketchObject.cpp
index 0e3314bab3..723e84cc4a 100644
--- a/src/Mod/Sketcher/App/SketchObject.cpp
+++ b/src/Mod/Sketcher/App/SketchObject.cpp
@@ -3405,6 +3405,7 @@ int SketchObject::exposeInternalGeometry(int GeoId)
                     case Sketcher::BSplineKnotPoint:
                         knotpoints[(*it)->InternalAlignmentIndex] = true;
                         knotgeoids[(*it)->InternalAlignmentIndex] = (*it)->First;
+                        break;
                     default:
                         return -1;
                 }
@@ -3731,12 +3732,20 @@ int SketchObject::deleteUnusedInternalGeometry(int GeoId, bool delgeoid)
 
         // First we search existing IA 
         std::vector<int> controlpointgeoids(bsp->countPoles());
-        std::vector<int> associatedcontraints(bsp->countPoles());
+        std::vector<int> cpassociatedcontraints(bsp->countPoles());
+        
+        std::vector<int> knotgeoids(bsp->countKnots());
+        std::vector<int> kassociatedcontraints(bsp->countKnots());
 
         std::vector<int>::iterator it;
         std::vector<int>::iterator ita;
 
-        for (it=controlpointgeoids.begin(), ita=associatedcontraints.begin(); it!=controlpointgeoids.end() && ita!=associatedcontraints.end(); ++it, ++ita) {
+        for (it=controlpointgeoids.begin(), ita=cpassociatedcontraints.begin(); it!=controlpointgeoids.end() && ita!=cpassociatedcontraints.end(); ++it, ++ita) {
+            (*it) = -1;
+            (*ita) = 0;
+        }
+        
+        for (it=knotgeoids.begin(), ita=kassociatedcontraints.begin(); it!=knotgeoids.end() && ita!=kassociatedcontraints.end(); ++it, ++ita) {
             (*it) = -1;
             (*ita) = 0;
         }
@@ -3750,6 +3759,9 @@ int SketchObject::deleteUnusedInternalGeometry(int GeoId, bool delgeoid)
                 case Sketcher::BSplineControlPoint:
                     controlpointgeoids[(*jt)->InternalAlignmentIndex] = (*jt)->First;
                     break;
+                case Sketcher::BSplineKnotPoint:
+                    knotgeoids[(*jt)->InternalAlignmentIndex] = (*jt)->First;
+                    break;
                 default:
                     return -1;
                 }
@@ -3758,7 +3770,7 @@ int SketchObject::deleteUnusedInternalGeometry(int GeoId, bool delgeoid)
 
         std::vector<int> delgeometries;
 
-        for (it=controlpointgeoids.begin(), ita=associatedcontraints.begin(); it!=controlpointgeoids.end() && ita!=associatedcontraints.end(); ++it, ++ita) {
+        for (it=controlpointgeoids.begin(), ita=cpassociatedcontraints.begin(); it!=controlpointgeoids.end() && ita!=cpassociatedcontraints.end(); ++it, ++ita) {
             if ((*it) != -1) {
                 // look for a circle at geoid index
                 for (std::vector< Sketcher::Constraint * >::const_iterator itc= vals.begin(); itc != vals.end(); ++itc) {
@@ -3795,6 +3807,22 @@ int SketchObject::deleteUnusedInternalGeometry(int GeoId, bool delgeoid)
             }
         }
 
+        for (it=knotgeoids.begin(), ita=kassociatedcontraints.begin(); it!=knotgeoids.end() && ita!=kassociatedcontraints.end(); ++it, ++ita) {
+            if ((*it) != -1) {
+                // look for a point at geoid index
+                for (std::vector< Sketcher::Constraint * >::const_iterator itc= vals.begin(); itc != vals.end(); ++itc) {
+                    if ((*itc)->Second == (*it) || (*itc)->First == (*it) || (*itc)->Third == (*it)) {
+                        (*ita)++;
+                    }
+                }
+                
+                if ( (*ita) < 2 ) { // IA
+                    delgeometries.push_back((*it));
+                }
+            }
+        }
+        
+        
         if(delgeoid)
             delgeometries.push_back(GeoId);