diff --git a/TeXmacs/progs/kernel/texmacs/tm-define-test.scm b/TeXmacs/progs/kernel/texmacs/tm-define-test.scm
index c39bab7ac0..1e8d0b219e 100644
--- a/TeXmacs/progs/kernel/texmacs/tm-define-test.scm
+++ b/TeXmacs/progs/kernel/texmacs/tm-define-test.scm
@@ -30,6 +30,7 @@
    (test "glue procedure" system 'system)
    (test "tm-defined" exec-interactive-command
                       'exec-interactive-command)
+   (test "anonymous function" (lambda (x) (+ x 1)) #f)
    (test "invalid input" 1 #f)))
 
 
diff --git a/TeXmacs/progs/kernel/texmacs/tm-define.scm b/TeXmacs/progs/kernel/texmacs/tm-define.scm
index e0e56489e5..f44d98fbb4 100644
--- a/TeXmacs/progs/kernel/texmacs/tm-define.scm
+++ b/TeXmacs/progs/kernel/texmacs/tm-define.scm
@@ -94,9 +94,10 @@
 (define-public (procedure-symbol-name fun)
   (cond ((symbol? fun) fun)
         ((string? fun) (string->symbol fun))
-        ((procedure? fun)
-         (with s-fun (ahash-ref tm-defined-name fun)
-           (if (symbol? s-fun) s-fun (string->symbol (object->string fun)))))
+        ((and (procedure? fun) (ahash-ref tm-defined-name fun))
+         (ahash-ref tm-defined-name fun))
+        ((and (procedure? fun) (string-alpha? (object->string fun)))
+         (string->symbol (object->string fun)))
         (else #f)))
 
 (define-public (procedure-string-name fun)