diff --git a/g10/trustdb.c b/g10/trustdb.c
index 92c1ca50a..0a98c129f 100644
--- a/g10/trustdb.c
+++ b/g10/trustdb.c
@@ -1505,6 +1505,10 @@ store_validation_status (ctrl_t ctrl, int depth,
 /* Returns a sanitized copy of the regexp (which might be "", but not
    NULL). */
 #ifndef DISABLE_REGEX
+/* Operator charactors except '.' and backslash.
+   See regex(7) on BSD.  */
+#define REGEXP_OPERATOR_CHARS "^[$()|*+?{"
+
 static char *
 sanitize_regexp(const char *old)
 {
@@ -1544,7 +1548,7 @@ sanitize_regexp(const char *old)
     {
       if(!escaped && old[start]=='\\')
 	escaped=1;
-      else if(!escaped && old[start]!='.')
+      else if (!escaped && strchr (REGEXP_OPERATOR_CHARS, old[start]))
 	new[idx++]='\\';
       else
 	escaped=0;