diff --git a/src/build/ChangeLog b/src/build/ChangeLog
index c52c8f18..000bd265 100644
--- a/src/build/ChangeLog
+++ b/src/build/ChangeLog
@@ -29,6 +29,10 @@ from 2.7.x to 2.8.0
 - exposing build_regex_for_exclude_mask() routine in tools module (was cli
   specific in line_tools module).
 
+from 2.7.15 to 2.7.16
+- fixed mask building of path exclusion (dar's -P option) when used with
+  regular expression (problem met while testing or merging a backup)
+
 from 2.7.14 to 2.7.15
 - updating libdar about CURLINFO_CONTENT_LENGTH_DOWNLOAD symbol which is
   reported as deprecated by recent libcurl libraries.
diff --git a/src/libdar/tools.cpp b/src/libdar/tools.cpp
index 4bb47bcf..0d7bf091 100644
--- a/src/libdar/tools.cpp
+++ b/src/libdar/tools.cpp
@@ -2407,13 +2407,15 @@ namespace libdar
 
 	for( ; it != prefix.end() ; ++it)
 	{
-	    if(isalnum(*it) || *it == '/' || *it == ' ')
-		result += *it;
-	    else
+	    if(*it == '.' || *it == '?' || *it == '+' || *it == '*' ||
+	       *it == '^' || *it == '$' || *it == '[' || *it == '|' ||
+	       *it == '{' || *it == '(' || *it == ')' || *it == '\\')
 	    {
 		result += '\\';
 		result += *it;
 	    }
+	    else
+		result += *it;
 	}
 
 	    // adding a trailing / if necessary