diff --git a/shell/i.cpp b/shell/i.cpp
index d6d9c88..87f29e8 100644
--- a/shell/i.cpp
+++ b/shell/i.cpp
@@ -249,7 +249,7 @@ void _isc(Session &session, std::string vspace_name, bool sort,
 struct _is_args
 {
     std::string vspace_name;
-    FxOS::Symbol symbol;
+    std::optional<FxOS::Symbol> symbol;
 };
 
 static struct _is_args parse_is(Session &session, Parser &parser)
@@ -272,14 +272,12 @@ static struct _is_args parse_is(Session &session, Parser &parser)
             s.type = FxOS::Symbol::Address;
             s.value = parser.expr(session.current_space);
         }
+        args.symbol = s;
     }
     else {
-        s.type = FxOS::Symbol::Address;
-        s.value = 0;
+        args.symbol = {};
     }
 
-    args.symbol = s;
-
 
     VirtualSpace *space = session.current_space;
     if(!args.vspace_name.empty()) {
@@ -298,7 +296,8 @@ static struct _is_args parse_is(Session &session, Parser &parser)
     return args;
 }
 
-void _is(Session &session, std::string vspace_name, FxOS::Symbol symbol)
+void _is(Session &session, std::string vspace_name,
+    std::optional<FxOS::Symbol> symbol)
 {
     VirtualSpace *space = session.current_space;
     if(!space) {
@@ -316,52 +315,41 @@ void _is(Session &session, std::string vspace_name, FxOS::Symbol symbol)
 
     std::vector<FxOS::Symbol> symbols;
 
-    if(symbol.type == FxOS::Symbol::Address && symbol.value == 0)
+    if(!symbol.has_value())
         symbols = space->symbols.symbols;
     else {
-        std::optional<std::string> name
-            = space->symbols.query(symbol.type, symbol.value);
+        FxOS::Symbol s = symbol.value();
+
+        std::optional<std::string> name = space->symbols.query(s.type, s.value);
 
         if(name.has_value())
-            symbol.name = name.value();
-        else if(symbol.type == FxOS::Symbol::Address) {
+            s.name = name.value();
+        else if(s.type == FxOS::Symbol::Address) {
             if(vspace_name.empty())
-                fmt::print(stderr,
-                    "\x1b[31;1merror:\x1b[0m no symbol exists for address 0x{:08x} in current virtual space\n",
-                    symbol.value);
+                FxOS_log(ERR,
+                    "no symbol exists for address 0x%08x in current virtual space",
+                    s.value);
             else
-                fmt::print(stderr,
-                    "\x1b[31;1merror:\x1b[0m no symbol exists for address 0x{:08x} in virtual space '{}'\n",
-                    symbol.value, vspace_name);
+                FxOS_log(ERR,
+                    "no symbol exists for syscall 0x%08x in virtual space '%s'",
+                    s.value, vspace_name);
 
             return;
         }
-        else if(symbol.type == FxOS::Symbol::Syscall) {
-            if(vspace_name.empty()) {
-                if(symbol.value < 0x1000)
-                    fmt::print(stderr,
-                        "\x1b[31;1merror:\x1b[0m no symbol exists for syscall %{:03x} in current virtual space\n",
-                        symbol.value);
-                else
-                    fmt::print(stderr,
-                        "\x1b[31;1merror:\x1b[0m no symbol exists for syscall %{:04x} in current virtual space\n",
-                        symbol.value);
-            }
-            else {
-                if(symbol.value < 0x1000)
-                    fmt::print(stderr,
-                        "\x1b[31;1merror:\x1b[0m no symbol exists for syscall %{:03x} in virtual space '{}'\n",
-                        symbol.value, vspace_name);
-                else
-                    fmt::print(stderr,
-                        "\x1b[31;1merror:\x1b[0m no symbol exists for syscall %{:04x} in virtual space '{}'\n",
-                        symbol.value, vspace_name);
-            }
+        else if(s.type == FxOS::Symbol::Syscall) {
+            if(vspace_name.empty())
+                FxOS_log(ERR,
+                    "no symbol exists for syscall %%%04x in current virtual space",
+                    s.value);
+            else
+                FxOS_log(ERR,
+                    "no symbol exists for syscall %%%04x in virtual space '%s'",
+                    s.value, vspace_name);
 
             return;
         }
 
-        symbols = {symbol};
+        symbols = {s};
     }
 
     for(auto const &s: symbols) {