diff --git a/src/Mod/Sketcher/Gui/EditDatumDialog.cpp b/src/Mod/Sketcher/Gui/EditDatumDialog.cpp
index 88db1b321b..8b7eca6c2b 100644
--- a/src/Mod/Sketcher/Gui/EditDatumDialog.cpp
+++ b/src/Mod/Sketcher/Gui/EditDatumDialog.cpp
@@ -50,6 +50,23 @@ using namespace SketcherGui;
 
 /* TRANSLATOR SketcherGui::EditDatumDialog */
 
+bool SketcherGui::checkConstraintName(const Sketcher::SketchObject* sketch,
+                                      std::string constraintName)
+{
+    if (constraintName != Base::Tools::getIdentifier(constraintName)) {
+        Gui::NotifyUserError(
+            sketch,
+            QT_TRANSLATE_NOOP("Notifications", "Value Error"),
+            QT_TRANSLATE_NOOP("Notifications",
+                              "Invalid constraint name (must only contain alphanumericals and "
+                              "underscores, and must not start with digit)"));
+        return false;
+    }
+
+    return true;
+}
+
+
 EditDatumDialog::EditDatumDialog(ViewProviderSketch* vp, int ConstrNbr)
     : ConstrNbr(ConstrNbr)
     , success(false)
@@ -213,15 +230,18 @@ void EditDatumDialog::accepted()
                 }
             }
 
-            QString constraintName = ui_ins_datum->name->text().trimmed();
-            if (constraintName.toStdString() != sketch->Constraints[ConstrNbr]->Name) {
-                std::string escapedstr =
-                    Base::Tools::escapedUnicodeFromUtf8(constraintName.toUtf8().constData());
-                escapedstr = Base::Tools::escapeQuotesFromString(escapedstr);
+            std::string constraintName = ui_ins_datum->name->text().trimmed().toStdString();
+            std::string currConstraintName = sketch->Constraints[ConstrNbr]->Name;
+            printf("datum");
+            if (constraintName != currConstraintName) {
+                if (!SketcherGui::checkConstraintName(sketch, constraintName)) {
+                    constraintName = currConstraintName;
+                }
+
                 Gui::cmdAppObjectArgs(sketch,
                                       "renameConstraint(%d, u'%s')",
                                       ConstrNbr,
-                                      escapedstr.c_str());
+                                      constraintName.c_str());
             }
 
             Gui::Command::commitCommand();
diff --git a/src/Mod/Sketcher/Gui/EditDatumDialog.h b/src/Mod/Sketcher/Gui/EditDatumDialog.h
index 64cb732af5..1aec82147e 100644
--- a/src/Mod/Sketcher/Gui/EditDatumDialog.h
+++ b/src/Mod/Sketcher/Gui/EditDatumDialog.h
@@ -38,6 +38,8 @@ namespace SketcherGui
 class ViewProviderSketch;
 class Ui_InsertDatum;
 
+bool checkConstraintName(const Sketcher::SketchObject* sketch, std::string constraintName);
+
 class EditDatumDialog: public QObject
 {
     Q_OBJECT
diff --git a/src/Mod/Sketcher/Gui/TaskSketcherConstraints.cpp b/src/Mod/Sketcher/Gui/TaskSketcherConstraints.cpp
index ac63cf052d..a0fc18624c 100644
--- a/src/Mod/Sketcher/Gui/TaskSketcherConstraints.cpp
+++ b/src/Mod/Sketcher/Gui/TaskSketcherConstraints.cpp
@@ -1223,13 +1223,16 @@ void TaskSketcherConstraints::onListWidgetConstraintsItemChanged(QListWidgetItem
     // b) that the text in the widget item, basename, is not ""
     // otherwise a checkbox change will trigger a rename on the first execution, bloating the
     // constraint icons with the default constraint name "constraint1, constraint2"
+    printf("task");
     if (newName != currConstraintName && !basename.empty()) {
-        std::string escapedstr = Base::Tools::escapedUnicodeFromUtf8(newName.c_str());
+        if (!SketcherGui::checkConstraintName(sketch, newName)) {
+            newName = currConstraintName;
+        }
 
         Gui::Command::openCommand(QT_TRANSLATE_NOOP("Command", "Rename sketch constraint"));
         try {
             Gui::cmdAppObjectArgs(
-                sketch, "renameConstraint(%d, u'%s')", it->ConstraintNbr, escapedstr.c_str());
+                sketch, "renameConstraint(%d, u'%s')", it->ConstraintNbr, newName.c_str());
             Gui::Command::commitCommand();
         }
         catch (const Base::Exception& e) {