diff --git a/shell/i.cpp b/shell/i.cpp
index a17412d..0d53f73 100644
--- a/shell/i.cpp
+++ b/shell/i.cpp
@@ -151,8 +151,21 @@ static struct _isc_args parse_isc(Session &session, Parser &parser)
 
     parser.accept_options();
 
+    VirtualSpace *space = session.current_space;
+    if(!args.vspace_name.empty()) {
+        space = session.get_space(args.vspace_name);
+        if(!space) {
+            std::string msg
+                = format("virtual space '%s' does not exist", args.vspace_name);
+            if(parser.completing())
+                throw Parser::CompletionRequest("_error", msg);
+            else
+                FxOS_log(ERR, "%s", msg);
+        }
+    }
+
     while(!parser.at_end())
-        args.addresses.push_back(parser.expr(session.current_space));
+        args.addresses.push_back(parser.expr(space));
 
     parser.end();
     return args;
@@ -173,6 +186,11 @@ void _isc(Session &session, std::string vspace_name, bool sort,
     std::vector<uint32_t> addresses)
 {
     VirtualSpace *space = session.current_space;
+    if(!space) {
+        FxOS_log(ERR, "no virtual space selected");
+        return;
+    }
+
     if(!vspace_name.empty())
         space = session.get_space(vspace_name);
 
@@ -185,7 +203,8 @@ void _isc(Session &session, std::string vspace_name, bool sort,
     if(!os) {
         if(!vspace_name.empty())
             FxOS_log(ERR, "OS analysis on '%s' failed", vspace_name);
-        FxOS_log(ERR, "OS analysis failed");
+        else
+            FxOS_log(ERR, "OS analysis failed");
         return;
     }