diff --git a/src/main/java/com/nutomic/syncthingandroid/fragments/SettingsFragment.java b/src/main/java/com/nutomic/syncthingandroid/fragments/SettingsFragment.java
index 05470dea..3674eba2 100644
--- a/src/main/java/com/nutomic/syncthingandroid/fragments/SettingsFragment.java
+++ b/src/main/java/com/nutomic/syncthingandroid/fragments/SettingsFragment.java
@@ -264,7 +264,7 @@ public class SettingsFragment extends PreferenceFragment
 
         // Avoid any code injection.
         if (preference.getKey().equals(STTRACE)) {
-            if (((String) o).matches("[a-z, ]*"))
+            if (((String) o).matches("[0-9a-z, ]*"))
                 requireRestart = true;
             else {
                 Toast.makeText(getActivity(), R.string.toast_invalid_sttrace, Toast.LENGTH_SHORT).show();
diff --git a/src/main/res/values/strings.xml b/src/main/res/values/strings.xml
index a9ffb372..896727d7 100644
--- a/src/main/res/values/strings.xml
+++ b/src/main/res/values/strings.xml
@@ -326,7 +326,7 @@ Please report any problems you encounter via Github.</string>
     <string name="sttrace_title">Debug Options</string>
 
     <!-- Toast after entering invalid STTRACE params -->
-    <string name="toast_invalid_sttrace">Only a-z and \',\' are allowed in STTRACE options</string>
+    <string name="toast_invalid_sttrace">Only 0-9, a-z and \',\' are allowed in STTRACE options</string>
 
     <!-- Title for the preference to reset Syncthing indexes -->
     <string name="streset_title">Reset Database</string>