--- a/libinterp/parse-tree/lex.ll	Thu Jul 31 15:49:21 2014 +0200
+++ b/libinterp/parse-tree/lex.ll	Fri Aug 01 12:10:05 2014 -0400
@@ -98,6 +98,17 @@
 #include <oct-parse.h>
 #include <oct-gperf.h>
 
+// FIXME: with bison 3.x, OCTAVE_STYPE appears in the generated
+// oct-parse.h file, but there is no definition for YYSTYPE, which is
+// needed by the code that is generated by flex.  I can't seem to find a
+// way to tell flex to use OCTAVE_STYPE instead of YYSTYPE in the code
+// it generates, or to tell bison to provide the definition of YYSTYPE
+// in the generated oct-parse.h file.
+
+#if defined (OCTAVE_STYPE_IS_DECLARED) && ! defined YYSTYPE
+#define YYSTYPE OCTAVE_STYPE
+#endif
+
 #if defined (GNULIB_NAMESPACE)
 // Calls to the following functions appear in the generated output from
 // flex without the namespace tag.  Redefine them so we will use them