diff --git a/pcpp/evaluator.py b/pcpp/evaluator.py
index 38abe20..498ec1f 100644
--- a/pcpp/evaluator.py
+++ b/pcpp/evaluator.py
@@ -357,7 +357,7 @@ def __gt__(self, other):
 
 # The subset of tokens from Preprocessor used in preprocessor expressions
 tokens = (
-   'CPP_ID', 'CPP_INTEGER', 'CPP_CHAR', 'CPP_STRING',
+   'CPP_ID', 'PP_NUMBER', 'CPP_CHAR', 'CPP_STRING',
    'CPP_PLUS', 'CPP_MINUS', 'CPP_STAR', 'CPP_FSLASH', 'CPP_PERCENT', 'CPP_BAR',
    'CPP_AMPERSAND', 'CPP_TILDE', 'CPP_HAT', 'CPP_LESS', 'CPP_GREATER', 'CPP_EXCLAMATION',
    'CPP_QUESTION', 'CPP_LPAREN', 'CPP_RPAREN',
@@ -394,8 +394,12 @@ def p_error(p):
         raise SyntaxError("at EOF")
 
 def p_expression_number(p):
-    'expression : CPP_INTEGER'
-    p[0] = Value(p[1])
+    'expression : PP_NUMBER'
+    try:
+        p[0] = Value(p[1])
+    except:
+        p[0] = p[1]
+
 
 def p_expression_character(p):
     'expression : CPP_CHAR'
diff --git a/pcpp/parser.py b/pcpp/parser.py
index 8e6a10a..6e55987 100644
--- a/pcpp/parser.py
+++ b/pcpp/parser.py
@@ -27,7 +27,7 @@
 # -----------------------------------------------------------------------------
 
 tokens = (
-   'CPP_ID','CPP_INTEGER', 'CPP_FLOAT', 'CPP_STRING', 'CPP_CHAR', 'CPP_WS', 'CPP_LINECONT', 'CPP_COMMENT1', 'CPP_COMMENT2',
+   'CPP_ID', 'PP_NUMBER', 'CPP_STRING', 'CPP_CHAR', 'CPP_WS', 'CPP_LINECONT', 'CPP_COMMENT1', 'CPP_COMMENT2',
    'CPP_POUND','CPP_DPOUND', 'CPP_PLUS', 'CPP_MINUS', 'CPP_STAR', 'CPP_FSLASH', 'CPP_PERCENT', 'CPP_BAR',
    'CPP_AMPERSAND', 'CPP_TILDE', 'CPP_HAT', 'CPP_LESS', 'CPP_GREATER', 'CPP_EQUAL', 'CPP_EXCLAMATION',
    'CPP_QUESTION', 'CPP_LPAREN', 'CPP_RPAREN', 'CPP_LBRACKET', 'CPP_RBRACKET', 'CPP_LCURLY', 'CPP_RCURLY',
@@ -111,15 +111,12 @@ def t_CPP_LINECONT(t):
 # Identifier
 t_CPP_ID = r'[A-Za-z_][\w_]*'
 
-# Integer literal
-def CPP_INTEGER(t):
-    r'(((((0x)|(0X))[0-9a-fA-F]+)|(\d+))([uU][lL]|[lL][uU]|[uU]|[lL])?)'
+# Preprocessor number
+def PP_NUMBER(t):
+    r'\.?\d(\.|[\w_]|\'[\w_]|[eEpP][-+])*'
     return t
 
-t_CPP_INTEGER = CPP_INTEGER
-
-# Floating literal
-t_CPP_FLOAT = r'((\d+)(\.\d+)(e(\+|-)?(\d+))?|(\d+)e(\+|-)?(\d+))([lL]|[fF])?'
+t_PP_NUMBER = PP_NUMBER
 
 # String literal
 def t_CPP_STRING(t):