fix for ruby 2.4

---
 src/conversions/basic/conversions.h  | 8 ++++----
 src/conversions/basic/plruby_basic.c | 4 ++--
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/src/conversions/basic/conversions.h b/src/conversions/basic/conversions.h
index 4d6b58d..d8e4378 100644
--- a/src/conversions/basic/conversions.h
+++ b/src/conversions/basic/conversions.h
@@ -2,10 +2,10 @@
     extern void plruby_require(char *);
 
     plruby_require("plruby/plruby_basic");
-    rb_hash_aset(plruby_classes, INT2NUM(OIDOID), rb_cFixnum);
-    rb_hash_aset(plruby_classes, INT2NUM(INT2OID), rb_cFixnum);
-    rb_hash_aset(plruby_classes, INT2NUM(INT4OID), rb_cFixnum);
-    rb_hash_aset(plruby_classes, INT2NUM(INT8OID), rb_cFixnum);
+    rb_hash_aset(plruby_classes, INT2NUM(OIDOID), rb_cInteger);
+    rb_hash_aset(plruby_classes, INT2NUM(INT2OID), rb_cInteger);
+    rb_hash_aset(plruby_classes, INT2NUM(INT4OID), rb_cInteger);
+    rb_hash_aset(plruby_classes, INT2NUM(INT8OID), rb_cInteger);
 
     rb_hash_aset(plruby_classes, INT2NUM(FLOAT4OID), rb_cFloat);
     rb_hash_aset(plruby_classes, INT2NUM(FLOAT8OID), rb_cFloat);
diff --git a/src/conversions/basic/plruby_basic.c b/src/conversions/basic/plruby_basic.c
index 2697224..2548be6 100644
--- a/src/conversions/basic/plruby_basic.c
+++ b/src/conversions/basic/plruby_basic.c
@@ -346,8 +346,8 @@ void Init_plruby_basic()
     id_to_i = rb_intern("to_i");
     id_usec = rb_intern("usec");
 
-    rb_define_singleton_method(rb_cFixnum, "from_datum", pl_fixnum_s_datum, 1);
-    rb_define_method(rb_cFixnum, "to_datum", pl_fixnum_to_datum, 1);
+    rb_define_singleton_method(rb_cInteger, "from_datum", pl_fixnum_s_datum, 1);
+    rb_define_method(rb_cInteger, "to_datum", pl_fixnum_to_datum, 1);
     rb_define_singleton_method(rb_cFloat, "from_datum", pl_float_s_datum, 1);
     rb_define_method(rb_cFloat, "to_datum", pl_float_to_datum, 1);
     rb_define_singleton_method(rb_cString, "from_datum", pl_str_s_datum, 1);
-- 
2.9.3