diff --git a/qucs-activefilter/qucsactivefilter.cpp b/qucs-activefilter/qucsactivefilter.cpp
index 8bc13dbb..42baa0b5 100644
--- a/qucs-activefilter/qucsactivefilter.cpp
+++ b/qucs-activefilter/qucsactivefilter.cpp
@@ -95,6 +95,7 @@ QucsActiveFilter::QucsActiveFilter(QWidget *parent)
 
     edtA1 = new QLineEdit("3");
     QDoubleValidator *val1 = new QDoubleValidator(0,100000,3);
+    val1->setLocale(QLocale::C);
     edtA1->setValidator(val1);
     edtA2 = new QLineEdit("20");
     edtA2->setValidator(val1);
diff --git a/qucs-attenuator/qucsattenuator.cpp b/qucs-attenuator/qucsattenuator.cpp
index 7a7dd7ee..e58c225d 100644
--- a/qucs-attenuator/qucsattenuator.cpp
+++ b/qucs-attenuator/qucsattenuator.cpp
@@ -107,6 +107,7 @@ QucsAttenuator::QucsAttenuator()
   inGrid->setSpacing(1);
 
   DoubleVal = new QDoubleValidator(this);
+  DoubleVal->setLocale(QLocale::C);
   DoubleVal->setBottom(0);
 
   LabelAtten = new QLabel(tr("Attenuation:"), InputGroup);
diff --git a/qucs-filter/qucsfilter.cpp b/qucs-filter/qucsfilter.cpp
index 2a203945..6e5517bd 100644
--- a/qucs-filter/qucsfilter.cpp
+++ b/qucs-filter/qucsfilter.cpp
@@ -148,6 +148,7 @@ QucsFilter::QucsFilter()
 
   IntVal = new QIntValidator(1, 200, this);
   DoubleVal = new QDoubleValidator(this);
+  DoubleVal->setLocale(QLocale::C);
 
   LabelOrder = new QLabel(tr("Order:"), this);
   gbox1->addWidget(LabelOrder, 3,0);
diff --git a/qucs-transcalc/qucstrans.cpp b/qucs-transcalc/qucstrans.cpp
index aedd6dcb..b83cc374 100644
--- a/qucs-transcalc/qucstrans.cpp
+++ b/qucs-transcalc/qucstrans.cpp
@@ -631,6 +631,7 @@ void QucsTranscalc::createPropItem (QGridLayout * parentGrid, TransValue * val,
   QLineEdit * e;
   QComboBox * c;
   QDoubleValidator * v = new QDoubleValidator (this);
+  v->setLocale(QLocale::C);
 
   // name label
   l = new QLabel (val->name);
diff --git a/qucs/components/optimizedialog.cpp b/qucs/components/optimizedialog.cpp
index 5389ee44..53c10e8a 100644
--- a/qucs/components/optimizedialog.cpp
+++ b/qucs/components/optimizedialog.cpp
@@ -59,6 +59,7 @@ OptimizeDialog::OptimizeDialog(Optimize_Sim *c_, Schematic *d_)
   Expr.setPattern("[\\w_]+");
   Validator = new QRegularExpressionValidator(Expr, this);
   numVal = new QDoubleValidator(this);
+  numVal->setLocale(QLocale::C);
   intVal = new QIntValidator(this);
 
   all = new QVBoxLayout(); // to provide the necessary size
diff --git a/qucs/diagrams/diagramdialog.cpp b/qucs/diagrams/diagramdialog.cpp
index 5558cdb1..c5518587 100644
--- a/qucs/diagrams/diagramdialog.cpp
+++ b/qucs/diagrams/diagramdialog.cpp
@@ -129,6 +129,7 @@ DiagramDialog::DiagramDialog(Diagram *d, QWidget *parent, Graph *currentGraph)
   Validator  = new QRegularExpressionValidator(Expr, this);
   ValInteger = new QIntValidator(0, 360, this);
   ValDouble  = new QDoubleValidator(-1e200, 1e200, 6, this);
+  ValDouble->setLocale(QLocale::C);
 
   QString NameY, NameZ;
   if((Diag->Name == "Rect") || (Diag->Name == "Curve")) {
diff --git a/qucs/diagrams/markerdialog.cpp b/qucs/diagrams/markerdialog.cpp
index 0698c2ba..5bf83364 100644
--- a/qucs/diagrams/markerdialog.cpp
+++ b/qucs/diagrams/markerdialog.cpp
@@ -47,7 +47,9 @@ MarkerDialog::MarkerDialog(Marker *pm_, QWidget *parent)
       XPosition->setText("0");
       XPosition->setEnabled(false);
   }
-  XPosition->setValidator(new QDoubleValidator(this));
+  QDoubleValidator *dblVal = new QDoubleValidator(this);
+  dblVal->setLocale(QLocale::C);
+  XPosition->setValidator(dblVal);
 
   g->addWidget(new QLabel(tr("Precision: ")), 0, 0);
   g->addWidget(Precision, 0, 1);
diff --git a/qucs/dialogs/exportdialog.cpp b/qucs/dialogs/exportdialog.cpp
index 21205edc..fce2810b 100644
--- a/qucs/dialogs/exportdialog.cpp
+++ b/qucs/dialogs/exportdialog.cpp
@@ -67,6 +67,7 @@ ExportDialog::ExportDialog(int w, int h, int wsel, int hsel, QString filename_,
     editResolutionY->setEnabled(false);
     editScale = new QLineEdit(QString::number(1.0));
     QDoubleValidator *val1 = new QDoubleValidator(0,20.0,2,this);
+    val1->setLocale(QLocale::C);
     editScale->setValidator(val1);
 
     cbxImgType = new QComboBox(this);
diff --git a/qucs/dialogs/matchdialog.cpp b/qucs/dialogs/matchdialog.cpp
index c29efd6e..d7b357e1 100644
--- a/qucs/dialogs/matchdialog.cpp
+++ b/qucs/dialogs/matchdialog.cpp
@@ -50,6 +50,7 @@ MatchDialog::MatchDialog(QWidget *parent)
 {
   setWindowTitle(tr("Create Matching Circuit"));
   DoubleVal = new QDoubleValidator(this);
+  DoubleVal->setLocale(QLocale::C);
 
   all = new QVBoxLayout(this);