diff --git a/src/cpp/ecl_fun_plugin.h b/src/cpp/ecl_fun_plugin.h
index 0cd0201..a1649ea 100644
--- a/src/cpp/ecl_fun_plugin.h
+++ b/src/cpp/ecl_fun_plugin.h
@@ -467,12 +467,15 @@ QVariant ecl_fun(const QByteArray& pkgFun,
     int p = pkgFun.indexOf(':');
     QByteArray pkg = (p == -1) ? "qml-user" : pkgFun.left(p);
     QByteArray fun = pkgFun.mid(pkgFun.lastIndexOf(':') + 1);
-    cl_object l_sym = cl_find_symbol(2,
-                                     make_constant_base_string(fun.toUpper().constData()),
-                                     cl_find_package(make_constant_base_string(pkg.toUpper().constData())));
-    if (l_sym != Cnil) {
-      symbol = l_sym;
-      lisp_functions[pkgFun] = symbol;
+    cl_object l_pkg = cl_find_package(make_constant_base_string(pkg.toUpper().constData()));
+    if (l_pkg != Cnil) {
+      cl_object l_sym = cl_find_symbol(2,
+                                       make_constant_base_string(fun.toUpper().constData()),
+                                       l_pkg);
+      if (cl_fboundp(l_sym) != Cnil) {
+        symbol = l_sym;
+        lisp_functions[pkgFun] = symbol;
+      }
     }
   }
   cl_object l_args = Cnil;
diff --git a/src/cpp/qt_ecl.cpp b/src/cpp/qt_ecl.cpp
index 06e43b1..8122703 100644
--- a/src/cpp/qt_ecl.cpp
+++ b/src/cpp/qt_ecl.cpp
@@ -45,12 +45,15 @@ QVariant ecl_fun(const QByteArray& pkgFun,
     int p = pkgFun.indexOf(':');
     QByteArray pkg = (p == -1) ? "qml-user" : pkgFun.left(p);
     QByteArray fun = pkgFun.mid(pkgFun.lastIndexOf(':') + 1);
-    cl_object l_sym = cl_find_symbol(2,
-                                     make_constant_base_string(fun.toUpper().constData()),
-                                     cl_find_package(make_constant_base_string(pkg.toUpper().constData())));
-    if (l_sym != Cnil) {
-      symbol = l_sym;
-      lisp_functions[pkgFun] = symbol;
+    cl_object l_pkg = cl_find_package(make_constant_base_string(pkg.toUpper().constData()));
+    if (l_pkg != Cnil) {
+      cl_object l_sym = cl_find_symbol(2,
+                                       make_constant_base_string(fun.toUpper().constData()),
+                                       l_pkg);
+      if (cl_fboundp(l_sym) != Cnil) {
+        symbol = l_sym;
+        lisp_functions[pkgFun] = symbol;
+      }
     }
   }
   cl_object l_args = Cnil;
diff --git a/src/lisp/qml.lisp b/src/lisp/qml.lisp
index e8d68f6..edca0dc 100644
--- a/src/lisp/qml.lisp
+++ b/src/lisp/qml.lisp
@@ -6,11 +6,12 @@
 (defvar *root-item*  nil) ; see macro 'with-root-item'
 
 (defun string-to-symbol (name)
-  (let ((upper (string-upcase name))
-        (p (position #\: name)))
+  (let* ((upper (string-upcase name))
+         (p (position #\: name))
+         (pkg (find-package (subseq upper 0 p))))
     (if p
-        (find-symbol (subseq upper (1+ (position #\: name :from-end t)))
-                     (subseq upper 0 p))
+        (and pkg (find-symbol (subseq upper (1+ (position #\: name :from-end t)))
+                              pkg))
         (find-symbol upper))))
 
 ;;; function calls from QML
@@ -25,7 +26,7 @@
                       (qt-object caller))))
     (if (fboundp fun)
         (apply fun arguments)
-        (let ((msg (format nil "[LQML:error] Lisp.call(): function ~S is undefined." function)))
+        (let ((msg (format nil "[LQML:error] Lisp.call(): ~S is undefined." function)))
           (when *break-on-errors*
             (break msg)
             (format *error-output* "~%~A~%" msg))))))