diff --git a/lisp/progmodes/gud.el b/lisp/progmodes/gud.el
index 4306f5daa02ad535efb6e9d9350b6c925318f02d..6b152b7b902e3b9a7743769fa4a310a360832638 100644
--- a/lisp/progmodes/gud.el
+++ b/lisp/progmodes/gud.el
@@ -1605,8 +1605,12 @@ and source-file directory for your debugger."
 
 ;; Last group is for return value, e.g. "> test.py(2)foo()->None"
 ;; Either file or function name may be omitted: "> <string>(0)?()"
+;;
+;; We use [:graph:] to be very allowing with regards to which
+;; characters we match in the file name shown in the prompt.
+;; (Of course, this matches the "<string>" case too.)
 (defvar gud-pdb-marker-regexp
-  "^> \\([-a-zA-Z0-9_/.:@ \\]*\\|<string>\\)(\\([0-9]+\\))\\([a-zA-Z0-9_]*\\|\\?\\|<module>\\)()\\(->[^\n\r]*\\)?[\n\r]")
+  "^> \\([[:graph:] \\]*\\)(\\([0-9]+\\))\\([a-zA-Z0-9_]*\\|\\?\\|<module>\\)()\\(->[^\n\r]*\\)?[\n\r]")
 
 (defvar gud-pdb-marker-regexp-file-group 1)
 (defvar gud-pdb-marker-regexp-line-group 2)