diff --git a/artiq/gui/explorer.py b/artiq/gui/explorer.py
index 1d82b2a99..6e9a81334 100644
--- a/artiq/gui/explorer.py
+++ b/artiq/gui/explorer.py
@@ -7,7 +7,7 @@ from pyqtgraph import LayoutWidget
 
 from artiq.protocols.sync_struct import Subscriber
 from artiq.protocols import pyon
-from artiq.gui.tools import DictSyncModel
+from artiq.gui.tools import DictSyncModel, force_spinbox_value
 from artiq.gui.scan import ScanController
 
 
@@ -73,7 +73,7 @@ class _NumberEntry(QtGui.QDoubleSpinBox):
         if procdesc["unit"]:
             self.setSuffix(" " + procdesc["unit"])
         if "default" in procdesc:
-            self.setValue(procdesc["default"])
+            force_spinbox_value(self, procdesc["default"])
 
     def get_argument_value(self):
         return self.value()
diff --git a/artiq/gui/scan.py b/artiq/gui/scan.py
index 1ec7c2dcf..2edafa579 100644
--- a/artiq/gui/scan.py
+++ b/artiq/gui/scan.py
@@ -1,6 +1,8 @@
 from quamash import QtGui
 from pyqtgraph import LayoutWidget
 
+from artiq.gui.tools import force_spinbox_value
+
 
 class _Range(LayoutWidget):
     def __init__(self, global_min, global_max, global_step, unit):
@@ -33,9 +35,9 @@ class _Range(LayoutWidget):
         self.addWidget(self.npoints, 0, 5)
 
     def set_values(self, min, max, npoints):
-        self.min.setValue(min)
-        self.max.setValue(max)
-        self.npoints.setValue(npoints)
+        force_spinbox_value(self.min, min)
+        force_spinbox_value(self.max, max)
+        force_spinbox_value(self.npoints, npoints)
 
     def get_values(self):
         return {
@@ -97,7 +99,7 @@ class ScanController(LayoutWidget):
             d = procdesc["default"]
             if d["ty"] == "NoScan":
                 self.noscan.setChecked(True)
-                self.v_noscan.setValue(d["value"])
+                force_spinbox_value(self.v_noscan, d["value"])
             elif d["ty"] == "LinearScan":
                 self.linear.setChecked(True)
                 self.v_linear.set_values(d["min"], d["max"], d["step"])
diff --git a/artiq/gui/tools.py b/artiq/gui/tools.py
index cab4e256d..536790549 100644
--- a/artiq/gui/tools.py
+++ b/artiq/gui/tools.py
@@ -1,6 +1,14 @@
 from quamash import QtCore
 
 
+def force_spinbox_value(spinbox, value):
+    if spinbox.minimum() > value:
+        spinbox.setMinimum(value)
+    if spinbox.maximum() < value:
+        spinbox.setMaximum(value)
+    spinbox.setValue(value)
+
+
 def short_format(v):
     t = type(v)
     if t is int or t is float: