diff --git a/extensions/wallet/signonviewer/SignonViewer.js b/extensions/wallet/signonviewer/SignonViewer.js
index 03627fa15336..0dc57d13bac2 100644
--- a/extensions/wallet/signonviewer/SignonViewer.js
+++ b/extensions/wallet/signonviewer/SignonViewer.js
@@ -65,7 +65,9 @@ function Startup()
     pref = null;
   }
 
-  LoadSignons();
+  if (!LoadSignons()) {
+    return; /* user failed to unlock the database */
+  }
   LoadReject();
   LoadNopreview();
   LoadNocapture();
@@ -78,6 +80,12 @@ function Startup()
 function LoadSignons()
 {
   signonList = signonviewer.GetSignonValue();
+  if (signonList.length == 1) {
+    /* user supplied invalid database key */
+    window.close();
+    return false;
+  }
+
   var delim = signonList[0];
   signonList = signonList.split(delim);
   for(var i = 1; i < signonList.length; i++)
@@ -89,6 +97,7 @@ function LoadSignons()
     var user = currSignon.substring(currSignon.lastIndexOf(":")+1,currSignon.length);
     AddItem("savesignonlist",[site,user],"signon_",i-1);
   }
+  return true;
 }
 
 // function : <SignonViewer.js>::DeleteSignon();
diff --git a/extensions/wallet/src/singsign.cpp b/extensions/wallet/src/singsign.cpp
index c711fe19fdfa..4a65836085f3 100644
--- a/extensions/wallet/src/singsign.cpp
+++ b/extensions/wallet/src/singsign.cpp
@@ -2851,6 +2851,7 @@ SINGSIGN_GetSignonListForViewer(nsAutoString& aSignonList)
 
   /* unlock the database */
   if (SI_LoadSignonData(PR_TRUE) != 0) {
+    aSignonList = "."; /* a list of length 1 tells viewer that database was not unlocked */ 
     /* don't display saved signons if user couldn't unlock the database */
     return;
   }