diff --git a/src/constrainteq.cpp b/src/constrainteq.cpp
index 680f3a0..fb1106c 100644
--- a/src/constrainteq.cpp
+++ b/src/constrainteq.cpp
@@ -152,6 +152,16 @@ void ConstraintBase::ModifyToSatisfy() {
         }
         double c = (a.Dot(b))/(a.Magnitude() * b.Magnitude());
         valA = acos(c)*180/PI;
+    } else if(type == Type::PT_ON_LINE) {
+        EntityBase *eln = SK.GetEntity(entityA);
+        EntityBase *ea = SK.GetEntity(eln->point[0]);
+        EntityBase *eb = SK.GetEntity(eln->point[1]);
+        EntityBase *ep = SK.GetEntity(ptA);
+        ExprVector exp = ep->PointGetExprsInWorkplane(workplane);
+        ExprVector exa = ea->PointGetExprsInWorkplane(workplane);
+        ExprVector exb = eb->PointGetExprsInWorkplane(workplane);
+        ExprVector exba = exb.Minus(exa);
+        SK.GetParam(valP)->val = exba.Dot(exp.Minus(exa))->Eval() / exba.Dot(exba)->Eval();
     } else {
         // We'll fix these ones up by looking at their symbolic equation;
         // that means no extra work.
@@ -185,7 +195,7 @@ void ConstraintBase::AddEq(IdList<Equation,hEquation> *l, const ExprVector &v,
     }
 }
 
-void ConstraintBase::Generate(IdList<Param,hParam> *l) const {
+void ConstraintBase::Generate(IdList<Param,hParam> *l) {
     switch(type) {
         case Type::PARALLEL:
         case Type::CUBIC_LINE_TANGENT:
@@ -195,7 +205,8 @@ void ConstraintBase::Generate(IdList<Param,hParam> *l) const {
         case Type::SAME_ORIENTATION:
         case Type::PT_ON_LINE: {
             Param p = {};
-            p.h = h.param(0);
+            valP = h.param(0);
+            p.h = valP;
             l->Add(&p);
             break;
         }
@@ -393,7 +404,7 @@ void ConstraintBase::GenerateEquations(IdList<Equation,hEquation> *l,
             ExprVector ea = a->PointGetExprsInWorkplane(workplane);
             ExprVector eb = b->PointGetExprsInWorkplane(workplane);
 
-            ExprVector ptOnLine = ea.Plus(eb.Minus(ea).ScaledBy(Expr::From(h.param(0))));
+            ExprVector ptOnLine = ea.Plus(eb.Minus(ea).ScaledBy(Expr::From(valP)));
             ExprVector eq = ptOnLine.Minus(ep);
 
             AddEq(l, eq);
@@ -599,7 +610,7 @@ void ConstraintBase::GenerateEquations(IdList<Equation,hEquation> *l,
                        bv = b->NormalExprsV(),
                        bn = b->NormalExprsN();
 
-            ExprVector eq = VectorsParallel3d(an, bn, h.param(0));
+            ExprVector eq = VectorsParallel3d(an, bn, valP);
             AddEq(l, eq);
             Expr *d1 = au.Dot(bv);
             Expr *d2 = au.Dot(bu);
@@ -690,7 +701,7 @@ void ConstraintBase::GenerateEquations(IdList<Equation,hEquation> *l,
             ExprVector b = line->VectorGetExprs();
 
             if(workplane.v == EntityBase::FREE_IN_3D.v) {
-                ExprVector eq = VectorsParallel3d(a, b, h.param(0));
+                ExprVector eq = VectorsParallel3d(a, b, valP);
                 AddEq(l, eq);
             } else {
                 EntityBase *w = SK.GetEntity(workplane);
@@ -744,7 +755,7 @@ void ConstraintBase::GenerateEquations(IdList<Equation,hEquation> *l,
             ExprVector b = eb->VectorGetExprsInWorkplane(workplane);
 
             if(workplane.v == EntityBase::FREE_IN_3D.v) {
-                ExprVector eq = VectorsParallel3d(a, b, h.param(0));
+                ExprVector eq = VectorsParallel3d(a, b, valP);
                 AddEq(l, eq);
             } else {
                 // We use expressions written in workplane csys, so we can assume the workplane
diff --git a/src/file.cpp b/src/file.cpp
index 45c233f..096a4ec 100644
--- a/src/file.cpp
+++ b/src/file.cpp
@@ -171,6 +171,7 @@ const SolveSpaceUI::SaveTable SolveSpaceUI::SAVED[] = {
     { 'c',  "Constraint.group.v",       'x',    &(SS.sv.c.group.v)            },
     { 'c',  "Constraint.workplane.v",   'x',    &(SS.sv.c.workplane.v)        },
     { 'c',  "Constraint.valA",          'f',    &(SS.sv.c.valA)               },
+    { 'c',  "Constraint.valP.v",        'x',    &(SS.sv.c.valP.v)             },
     { 'c',  "Constraint.ptA.v",         'x',    &(SS.sv.c.ptA.v)              },
     { 'c',  "Constraint.ptB.v",         'x',    &(SS.sv.c.ptB.v)              },
     { 'c',  "Constraint.entityA.v",     'x',    &(SS.sv.c.entityA.v)          },
@@ -573,7 +574,7 @@ void SolveSpaceUI::UpgradeLegacyData() {
     SK.param.DeepCopyInto(&oldParam);
     SS.GenerateAll(SolveSpaceUI::Generate::REGEN);
 
-    auto AllParamsExistFor = [&](const Constraint &c) {
+    auto AllParamsExistFor = [&](Constraint &c) {
         IdList<Param,hParam> param = {};
         c.Generate(&param);
         bool allParamsExist = true;
diff --git a/src/lib.cpp b/src/lib.cpp
index cad8058..4e5e7fd 100644
--- a/src/lib.cpp
+++ b/src/lib.cpp
@@ -132,7 +132,7 @@ default: dbp("bad entity type %d", se->type); return;
 
         SK.entity.Add(&e);
     }
-
+    IdList<Param, hParam> params = {};
     for(i = 0; i < ssys->constraints; i++) {
         Slvs_Constraint *sc = &(ssys->constraint[i]);
         ConstraintBase c = {};
@@ -192,6 +192,17 @@ default: dbp("bad constraint type %d", sc->type); return;
         c.other         = (sc->other) ? true : false;
         c.other2        = (sc->other2) ? true : false;
 
+        c.Generate(&params);
+        if(params.n > 0) {
+            for(Param &p : params) {
+                p.h = SK.param.AddAndAssignId(&p);
+                c.valP = p.h;
+                SYS.param.Add(&p);
+            }
+            params.Clear();
+            c.ModifyToSatisfy();
+        }
+
         SK.constraint.Add(&c);
     }
 
diff --git a/src/sketch.h b/src/sketch.h
index c0ba682..4c85089 100644
--- a/src/sketch.h
+++ b/src/sketch.h
@@ -627,6 +627,7 @@ public:
 
     // These are the parameters for the constraint.
     double      valA;
+    hParam      valP;
     hEntity     ptA;
     hEntity     ptB;
     hEntity     entityA;
@@ -641,7 +642,7 @@ public:
 
     bool HasLabel() const;
 
-    void Generate(IdList<Param, hParam> *param) const;
+    void Generate(IdList<Param, hParam> *param);
 
     void GenerateEquations(IdList<Equation,hEquation> *entity,
                            bool forReference = false) const;