diff --git a/tools/debugedit.c b/tools/debugedit.c

index abd2ca4..a271b91 100644

--- a/tools/debugedit.c

+++ b/tools/debugedit.c

@@ -662,7 +662,8 @@ canonicalize_path (const char *s, char *d)

 /* Returns the rest of PATH if it starts with DIR_PREFIX, skipping any

    / path separators, or NULL if PATH doesn't start with

    DIR_PREFIX. Might return the empty string if PATH equals DIR_PREFIX

-   (modulo trailing slashes). Never returns path starting with '/'. */

+   (modulo trailing slashes). Never returns path starting with '/'.

+   Note that DIR_PREFIX itself should NOT end with a '/'.  */

 static const char *

 skip_dir_prefix (const char *path, const char *dir_prefix)

 {

@@ -670,12 +671,17 @@ skip_dir_prefix (const char *path, const char *dir_prefix)

   if (strncmp (path, dir_prefix, prefix_len) == 0)

     {

       path += prefix_len;

+      /* Unless path == dir_prefix there should be at least one '/'

+	 in the path (which we will skip).  Otherwise the path has

+	 a different (longer) directory prefix.  */

+      if (*path != '\0' && !IS_DIR_SEPARATOR (*path))

+	return NULL;

       while (IS_DIR_SEPARATOR (path[0]))

 	path++;

       return path;

     }

-  return 0;

+  return NULL;

 }

 /* Most strings will be in the existing debug string table. But to