diff --git a/configure.ac b/configure.ac
index 8d5ac96..103eba5 100644
--- a/configure.ac
+++ b/configure.ac
@@ -223,6 +223,7 @@ AC_CHECK_ALIGNOF(double)
 AC_CHECK_ALIGNOF(long double)
 AC_CHECK_SIZEOF(off_t)
 AC_CHECK_SIZEOF(int)
+AC_CHECK_SIZEOF(long)
 AC_CHECK_SIZEOF(wchar_t, , [[
 #include <wchar.h>]])
 AC_CHECK_SIZEOF(OOP, , [[
diff --git a/lib-src/pointer-set.c b/lib-src/pointer-set.c
index 417d926..8a48c6e 100644
--- a/lib-src/pointer-set.c
+++ b/lib-src/pointer-set.c
@@ -24,6 +24,8 @@ MA 02110-1301, USA.  */
 
 #include "pointer-set.h"
 
+enum { false, true };
+
 /* A pointer set is represented as a simple open-addressing hash
    table.  Simplifications: The hash code is based on the value of the
    pointer, not what it points to.  The number of buckets is always a