diff --git a/src/libexpr/lexer.l b/src/libexpr/lexer.l
index 5fdcb25dd..7a6e48215 100644
--- a/src/libexpr/lexer.l
+++ b/src/libexpr/lexer.l
@@ -85,7 +85,7 @@ static Expr * unescapeStr(SymbolTable & symbols, const char * s)
 
 ID          [a-zA-Z\_][a-zA-Z0-9\_\'\-]*
 INT         [0-9]+
-FLOAT       (([1-9][0-9]*\.?[0-9]*)|(\.[0-9]+))([Ee][+-]?[0-9]+)?
+FLOAT       (([1-9][0-9]*\.[0-9]*)|(0?\.[0-9]+))([Ee][+-]?[0-9]+)?
 PATH        [a-zA-Z0-9\.\_\-\+]*(\/[a-zA-Z0-9\.\_\-\+]+)+
 HPATH       \~(\/[a-zA-Z0-9\.\_\-\+]+)+
 SPATH       \<[a-zA-Z0-9\.\_\-\+]+(\/[a-zA-Z0-9\.\_\-\+]+)*\>