diff --git a/src/asciireadersettings.cpp b/src/asciireadersettings.cpp
--- a/src/asciireadersettings.cpp
+++ b/src/asciireadersettings.cpp
@@ -1,5 +1,5 @@
 /*
-  Copyright © 2017 Hasan Yavuz Özderya
+  Copyright © 2019 Hasan Yavuz Özderya
 
   This file is part of serialplot.
 
@@ -21,6 +21,7 @@
 #include <QRegularExpression>
 
 #include "utils.h"
+#include "defines.h"
 #include "setting_defines.h"
 
 #include "asciireadersettings.h"
@@ -35,6 +36,8 @@ AsciiReaderSettings::AsciiReaderSettings
     auto validator = new QRegularExpressionValidator(QRegularExpression("[^\\d]?"), this);
     ui->leDelimiter->setValidator(validator);
 
+    ui->spNumOfChannels->setMaximum(MAX_NUM_CHANNELS);
+
     connect(ui->rbComma, &QAbstractButton::toggled,
             this, &AsciiReaderSettings::delimiterToggled);
     connect(ui->rbSpace, &QAbstractButton::toggled,
diff --git a/src/binarystreamreadersettings.cpp b/src/binarystreamreadersettings.cpp
--- a/src/binarystreamreadersettings.cpp
+++ b/src/binarystreamreadersettings.cpp
@@ -1,5 +1,5 @@
 /*
-  Copyright © 2016 Hasan Yavuz Özderya
+  Copyright © 2019 Hasan Yavuz Özderya
 
   This file is part of serialplot.
 
@@ -21,6 +21,7 @@
 #include "ui_binarystreamreadersettings.h"
 
 #include "utils.h"
+#include "defines.h"
 #include "setting_defines.h"
 
 BinaryStreamReaderSettings::BinaryStreamReaderSettings(QWidget *parent) :
@@ -29,6 +30,8 @@ BinaryStreamReaderSettings::BinaryStream
 {
     ui->setupUi(this);
 
+    ui->spNumOfChannels->setMaximum(MAX_NUM_CHANNELS);
+
     // Note: if directly connected we get a runtime warning on incompatible signal arguments
     connect(ui->spNumOfChannels, SELECT<int>::OVERLOAD_OF(&QSpinBox::valueChanged),
             [this](int value)
diff --git a/src/defines.h b/src/defines.h
--- a/src/defines.h
+++ b/src/defines.h
@@ -1,5 +1,5 @@
 /*
-  Copyright © 2016 Hasan Yavuz Özderya
+  Copyright © 2019 Hasan Yavuz Özderya
 
   This file is part of serialplot.
 
@@ -17,4 +17,12 @@
   along with serialplot.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-const char* BUG_REPORT_URL = "https://bitbucket.org/hyOzd/serialplot/issues/new";
+#ifndef DEFINES_H
+#define DEFINES_H
+
+const char BUG_REPORT_URL[] = "https://bitbucket.org/hyOzd/serialplot/issues/new";
+
+/// Maximum number of channels that can be set by user
+const unsigned MAX_NUM_CHANNELS = 64;
+
+#endif  // DEFINES_H
diff --git a/src/demoreadersettings.cpp b/src/demoreadersettings.cpp
--- a/src/demoreadersettings.cpp
+++ b/src/demoreadersettings.cpp
@@ -1,5 +1,5 @@
 /*
-  Copyright © 2018 Hasan Yavuz Özderya
+  Copyright © 2019 Hasan Yavuz Özderya
 
   This file is part of serialplot.
 
@@ -21,6 +21,7 @@
 #include "ui_demoreadersettings.h"
 
 #include "utils.h"
+#include "defines.h"
 
 DemoReaderSettings::DemoReaderSettings(QWidget *parent) :
     QWidget(parent),
@@ -28,6 +29,8 @@ DemoReaderSettings::DemoReaderSettings(Q
 {
     ui->setupUi(this);
 
+    ui->spNumChannels->setMaximum(MAX_NUM_CHANNELS);
+
     connect(ui->spNumChannels, SELECT<int>::OVERLOAD_OF(&QSpinBox::valueChanged),
             [this](int value)
             {
diff --git a/src/framedreadersettings.cpp b/src/framedreadersettings.cpp
--- a/src/framedreadersettings.cpp
+++ b/src/framedreadersettings.cpp
@@ -1,5 +1,5 @@
 /*
-  Copyright © 2016 Hasan Yavuz Özderya
+  Copyright © 2019 Hasan Yavuz Özderya
 
   This file is part of serialplot.
 
@@ -20,6 +20,7 @@
 #include <QButtonGroup>
 
 #include "utils.h"
+#include "defines.h"
 #include "setting_defines.h"
 #include "framedreadersettings.h"
 #include "ui_framedreadersettings.h"
@@ -32,6 +33,7 @@ FramedReaderSettings::FramedReaderSettin
 
     ui->leSyncWord->setMode(false); // hex mode
     ui->leSyncWord->setText("AA BB");
+    ui->spNumOfChannels->setMaximum(MAX_NUM_CHANNELS);
 
     connect(ui->cbChecksum, &QCheckBox::toggled,
             [this](bool enabled)