diff --git a/examples/python3.g b/examples/python3.g
index 61dc1ee..bb5a4e8 100644
--- a/examples/python3.g
+++ b/examples/python3.g
@@ -165,7 +165,7 @@ string: STRING | LONG_STRING
 // Tokens
 
 NAME: /[a-zA-Z_]\w*/
-COMMENT: /\#[^\n]*/
+COMMENT: /#[^\n]*/
 _NEWLINE: ( /\r?\n[\t ]*/ | COMMENT )+
 
 
@@ -177,8 +177,8 @@ _NEWLINE: ( /\r?\n[\t ]*/ | COMMENT )+
 
 // STRING : /[ub]?r?("(?!"").*?(?<!\\)(\\\\)*?"|'(?!'').*?(?<!\\)(\\\\)*?')/
 // LONG_STRING: /(?s)[ub]?r?(""".*?(?<!\\)(\\\\)*?"""|'''.*?(?<!\\)(\\\\)*?''')/
-STRING : /(?i)[ub]?r?("(?!"").*?(?<!\\\\)(\\\\\\\\)*?"|'(?!'').*?(?<!\\\\)(\\\\\\\\)*?')/
-LONG_STRING: /(?i)(?s)[ub]?r?(""".*?(?<!\\\\)(\\\\\\\\)*?"""|'''.*?(?<!\\\\)(\\\\\\\\)*?''')/
+STRING : /(?i)[ubf]?r?("(?!"").*?(?<!\\\\)(\\\\\\\\)*?"|'(?!'').*?(?<!\\\\)(\\\\\\\\)*?')/
+LONG_STRING: /(?i)(?s)[ubf]?r?(""".*?(?<!\\\\)(\\\\\\\\)*?"""|'''.*?(?<!\\\\)(\\\\\\\\)*?''')/
 
 DEC_NUMBER: /(?i)[1-9]\d*l?/
 HEX_NUMBER: /(?i)0x[\da-f]*l?/
diff --git a/lark/load_grammar.py b/lark/load_grammar.py
index 3b6cdf4..f04e3c0 100644
--- a/lark/load_grammar.py
+++ b/lark/load_grammar.py
@@ -77,7 +77,7 @@ TOKENS = {
     '_TO': '->',
     '_IGNORE': r'%ignore',
     '_IMPORT': r'%import',
-    'NUMBER': '\d+',
+    'NUMBER': r'\d+',
 }
 
 RULES = {
@@ -294,7 +294,9 @@ def _literal_to_pattern(literal):
         flags = None
 
     assert v[0] == v[-1] and v[0] in '"/'
-    x = v[1:-1].replace("'", r"\'")
+    x = v[1:-1]
+    x = re.sub(r'(\\[wd/]|\\\[|\\\])', r'\\\1', x)
+    x = x.replace("'", r"\'")
     s = literal_eval("u'''%s'''" % x)
     return { 'STRING': PatternStr,
              'REGEXP': PatternRE }[literal.type](s, flags)
diff --git a/lark/tools/nearley.py b/lark/tools/nearley.py
index c6f9a2d..107b8ae 100644
--- a/lark/tools/nearley.py
+++ b/lark/tools/nearley.py
@@ -30,7 +30,7 @@ nearley_grammar = r"""
     js: JS?
 
     NAME: /[a-zA-Z_$]\w*/
-    COMMENT: /\#[^\n]*/
+    COMMENT: /#[^\n]*/
     REGEXP: /\[.*?\]/
     STRING: /".*?"/