diff --git a/gpxsee.pro b/gpxsee.pro
index ea3081b3..e094c499 100644
--- a/gpxsee.pro
+++ b/gpxsee.pro
@@ -93,7 +93,8 @@ HEADERS += src/config.h \
     src/ozf.h \
     src/datum.h \
     src/maplist.h \
-    src/albersequal.h
+    src/albersequal.h \
+    src/oddspinbox.h
 SOURCES += src/main.cpp \
     src/gui.cpp \
     src/poi.cpp \
@@ -160,7 +161,8 @@ SOURCES += src/main.cpp \
     src/ozf.cpp \
     src/datum.cpp \
     src/maplist.cpp \
-    src/albersequal.cpp
+    src/albersequal.cpp \
+    src/oddspinbox.cpp
 RESOURCES += gpxsee.qrc
 TRANSLATIONS = lang/gpxsee_cs.ts \
     lang/gpxsee_sv.ts \
diff --git a/src/oddspinbox.cpp b/src/oddspinbox.cpp
new file mode 100644
index 00000000..0365e47a
--- /dev/null
+++ b/src/oddspinbox.cpp
@@ -0,0 +1,22 @@
+#include "oddspinbox.h"
+
+#include <QDebug>
+
+OddSpinBox::OddSpinBox(QWidget *parent) : QSpinBox(parent)
+{
+	setSingleStep(2);
+	setMinimum(1);
+}
+
+QValidator::State OddSpinBox::validate(QString &text, int &pos) const
+{
+	Q_UNUSED(pos);
+	bool ok;
+	int val;
+
+	val = text.toInt(&ok);
+	if (!ok || val < 0 || val % 2 == 0)
+		return QValidator::Invalid;
+
+	return QValidator::Acceptable;
+}
diff --git a/src/oddspinbox.h b/src/oddspinbox.h
new file mode 100644
index 00000000..fcf97c5b
--- /dev/null
+++ b/src/oddspinbox.h
@@ -0,0 +1,15 @@
+#ifndef ODDSPINBOX_H
+#define ODDSPINBOX_H
+
+#include <QSpinBox>
+
+class OddSpinBox : public QSpinBox
+{
+public:
+	OddSpinBox(QWidget *parent = 0);
+
+protected:
+	QValidator::State validate(QString &text, int &pos) const;
+};
+
+#endif // ODDSPINBOX_H
diff --git a/src/optionsdialog.cpp b/src/optionsdialog.cpp
index 63238671..7bc5f694 100644
--- a/src/optionsdialog.cpp
+++ b/src/optionsdialog.cpp
@@ -14,6 +14,7 @@
 #include "icons.h"
 #include "colorbox.h"
 #include "stylecombobox.h"
+#include "oddspinbox.h"
 #include "optionsdialog.h"
 
 #define MENU_MARGIN 20
@@ -122,19 +123,19 @@ QWidget *OptionsDialog::createDataPage()
 {
 	QString filterToolTip = tr("Moving average window size");
 
-	_elevationFilter = new QSpinBox();
+	_elevationFilter = new OddSpinBox();
 	_elevationFilter->setValue(_options->elevationFilter);
 	_elevationFilter->setToolTip(filterToolTip);
-	_speedFilter = new QSpinBox();
+	_speedFilter = new OddSpinBox();
 	_speedFilter->setValue(_options->speedFilter);
 	_speedFilter->setToolTip(filterToolTip);
-	_heartRateFilter = new QSpinBox();
+	_heartRateFilter = new OddSpinBox();
 	_heartRateFilter->setValue(_options->heartRateFilter);
 	_heartRateFilter->setToolTip(filterToolTip);
-	_cadenceFilter = new QSpinBox();
+	_cadenceFilter = new OddSpinBox();
 	_cadenceFilter->setValue(_options->cadenceFilter);
 	_cadenceFilter->setToolTip(filterToolTip);
-	_powerFilter = new QSpinBox();
+	_powerFilter = new OddSpinBox();
 	_powerFilter->setValue(_options->powerFilter);
 	_powerFilter->setToolTip(filterToolTip);
 
diff --git a/src/optionsdialog.h b/src/optionsdialog.h
index ae65d73c..133225c4 100644
--- a/src/optionsdialog.h
+++ b/src/optionsdialog.h
@@ -7,6 +7,7 @@
 
 class ColorBox;
 class StyleComboBox;
+class OddSpinBox;
 class QSpinBox;
 class QDoubleSpinBox;
 class QComboBox;
@@ -78,11 +79,11 @@ private:
 	QSpinBox *_graphWidth;
 	QCheckBox *_graphAA;
 	// Data
-	QSpinBox *_elevationFilter;
-	QSpinBox *_speedFilter;
-	QSpinBox *_heartRateFilter;
-	QSpinBox *_cadenceFilter;
-	QSpinBox *_powerFilter;
+	OddSpinBox *_elevationFilter;
+	OddSpinBox *_speedFilter;
+	OddSpinBox *_heartRateFilter;
+	OddSpinBox *_cadenceFilter;
+	OddSpinBox *_powerFilter;
 	QCheckBox *_outlierEliminate;
 	QDoubleSpinBox *_pauseSpeed;
 	QSpinBox *_pauseInterval;