diff --git a/graphite_api/render/grammar.py b/graphite_api/render/grammar.py
index d29e11f..1a71521 100644
--- a/graphite_api/render/grammar.py
+++ b/graphite_api/render/grammar.py
@@ -60,7 +60,8 @@
 equal = Literal('=').suppress()
 backslash = Literal('\\').suppress()
 
-symbols = '''(){},=.'"\\'''
+unallowedSymbols = '''(){},=.\\'''
+allowedSymbols = ''''"'''
 arg = Group(
     boolean |
     number |
@@ -83,8 +84,8 @@
 )('call')
 
 # Metric pattern (aka. pathExpression)
-validMetricChars = ''.join((set(printables) - set(symbols)))
-escapedChar = backslash + Word(symbols, exact=1)
+validMetricChars = ''.join((set(printables) - set(unallowedSymbols)))
+escapedChar = backslash + Word(unallowedSymbols + allowedSymbols, exact=1)
 partialPathElem = Combine(
     OneOrMore(
         escapedChar | Word(validMetricChars)