--- a/ext/linalg.c
+++ b/ext/linalg.c
@@ -14,6 +14,7 @@
 #include "rb_gsl_array.h"
 #include "rb_gsl_common.h"
 #include "rb_gsl_linalg.h"
+#include "porting.h"
 
 static VALUE cgsl_matrix_LU;
 static VALUE cgsl_matrix_QR;
@@ -71,7 +72,7 @@ static VALUE rb_gsl_linalg_LU_decomposit
   Data_Get_Struct(omatrix, gsl_matrix, mtmp);
   if (flag == LINALG_DECOMP_BANG) {
     m = mtmp;
-    RBASIC(omatrix)->klass = cgsl_matrix_LU;
+    rb_obj_reveal(omatrix, cgsl_matrix_LU);
     objm = omatrix;
   } else {
     m = make_matrix_clone(mtmp);
@@ -692,7 +693,7 @@ static VALUE rb_gsl_linalg_QR_LQ_decompo
     fdecomp = &gsl_linalg_QR_decomp;
     m = mtmp;
     mdecomp = omatrix;
-    RBASIC(mdecomp)->klass = cgsl_matrix_QR;
+    rb_obj_reveal(mdecomp, cgsl_matrix_QR);
     break;
 #ifdef GSL_1_6_LATER
   case LINALG_LQ_DECOMP:
@@ -704,7 +705,7 @@ static VALUE rb_gsl_linalg_QR_LQ_decompo
     fdecomp = &gsl_linalg_LQ_decomp;
     m = mtmp;
     mdecomp = omatrix;
-    RBASIC(mdecomp)->klass = cgsl_matrix_LQ;
+    rb_obj_reveal(mdecomp, cgsl_matrix_LQ);
     break;
 #endif
   default:
@@ -731,7 +732,7 @@ static VALUE rb_gsl_linalg_QR_LQ_decompo
       vtau = Data_Wrap_Struct(cgsl_vector_tau, 0, gsl_vector_free, tau);
       return rb_ary_new3(2, mdecomp, vtau);
     } else {
-      RBASIC(argv[itmp])->klass = cgsl_vector_tau;
+      rb_obj_reveal(argv[itmp], cgsl_vector_tau);
       return mdecomp;
     }
     break;
@@ -740,7 +741,7 @@ static VALUE rb_gsl_linalg_QR_LQ_decompo
    if (argc == itmp) {
       return Data_Wrap_Struct(cgsl_vector_tau, 0, gsl_vector_free, tau);
     } else {
-      RBASIC(argv[itmp])->klass = cgsl_vector_tau;
+      rb_obj_reveal(argv[itmp], cgsl_vector_tau);
       return INT2FIX(status);
     }
     break;
@@ -1628,14 +1629,14 @@ static VALUE rb_gsl_linalg_QRLQPT_decomp
   norm = gsl_vector_alloc(size0);
   switch (flag) {
   case LINALG_QRPT:
-    RBASIC(vA)->klass = cgsl_matrix_QRPT;
+    rb_obj_reveal(vA, cgsl_matrix_QRPT);
     vtau = Data_Wrap_Struct(cgsl_vector_tau, 0, gsl_vector_free, tau);
     vp = Data_Wrap_Struct(cgsl_permutation, 0, gsl_permutation_free, p);
     gsl_linalg_QRPT_decomp(A, tau, p, &signum, norm);
     break;
 #ifdef GSL_1_6_LATER
   case LINALG_PTLQ:
-    RBASIC(vA)->klass = cgsl_matrix_PTLQ;
+    rb_obj_reveal(vA, cgsl_matrix_PTLQ);
     vtau = Data_Wrap_Struct(cgsl_vector_tau, 0, gsl_vector_free, tau);
     vp = Data_Wrap_Struct(cgsl_permutation, 0, gsl_permutation_free, p);
     gsl_linalg_PTLQ_decomp(A, tau, p, &signum, norm);
--- a/ext/linalg_complex.c
+++ b/ext/linalg_complex.c
@@ -14,6 +14,7 @@
 #include "rb_gsl_array.h"
 #include "rb_gsl_common.h"
 #include "rb_gsl_linalg.h"
+#include "porting.h"
 
 EXTERN VALUE mgsl_linalg;
 EXTERN VALUE cgsl_complex;
@@ -51,8 +52,8 @@ VALUE rb_gsl_linalg_complex_LU_decomp(in
   case 0:
     p = gsl_permutation_alloc(size);
     gsl_linalg_complex_LU_decomp(m, p, &signum);
-    if (itmp == 1) RBASIC(argv[0])->klass = cgsl_matrix_complex_LU;
-    else RBASIC(obj)->klass = cgsl_matrix_complex_LU;
+    if (itmp == 1) rb_obj_reveal(argv[0], cgsl_matrix_complex_LU);
+    else rb_obj_reveal(obj, cgsl_matrix_complex_LU);
     obj2 = Data_Wrap_Struct(cgsl_permutation, 0, gsl_permutation_free, p);
     return rb_ary_new3(2, obj2, INT2FIX(signum));
     break;
@@ -60,8 +61,8 @@ VALUE rb_gsl_linalg_complex_LU_decomp(in
     CHECK_PERMUTATION(argv[itmp]);
     Data_Get_Struct(argv[itmp], gsl_permutation, p);
     gsl_linalg_complex_LU_decomp(m, p, &signum);
-    if (itmp == 1) RBASIC(argv[0])->klass = cgsl_matrix_complex_LU;
-    else RBASIC(obj)->klass = cgsl_matrix_complex_LU;
+    if (itmp == 1) rb_obj_reveal(argv[0], cgsl_matrix_complex_LU);
+    else rb_obj_reveal(obj, cgsl_matrix_complex_LU);
     return INT2FIX(signum);
     break;
   default:
--- a/ext/ool.c
+++ b/ext/ool.c
@@ -2,6 +2,7 @@
 #include "rb_gsl.h"
 #include "rb_gsl_array.h"
 #include <ool/ool_conmin.h>
+#include "porting.h"
 
 static VALUE cool_conmin_function;
 static VALUE cool_conmin_constraint;
@@ -770,7 +771,7 @@ static VALUE rb_ool_conmin_pgrad_paramet
 	VALUE ary;
 	ool_conmin_parameters_default(ool_conmin_minimizer_pgrad, (void*) &P);
 	ary = create_parameters_ary_pgrad(&P);
-	RBASIC(ary)->klass = cool_conmin_pgrad_parameters;
+	rb_obj_reveal(ary, cool_conmin_pgrad_parameters);
 	return ary;
 }
 
@@ -780,7 +781,7 @@ static VALUE rb_ool_conmin_spg_parameter
 	VALUE ary;
 	ool_conmin_parameters_default(ool_conmin_minimizer_spg, (void*) &P);
 	ary = create_parameters_ary_spg(&P);	
-	RBASIC(ary)->klass = cool_conmin_spg_parameters;	
+	rb_obj_reveal(ary, cool_conmin_spg_parameters);	
 	return ary;	
 }
 
@@ -790,7 +791,7 @@ static VALUE rb_ool_conmin_gencan_parame
 	VALUE ary;
 	ool_conmin_parameters_default(ool_conmin_minimizer_gencan, (void*) &P);
 	ary = create_parameters_ary_gencan(&P);		
-	RBASIC(ary)->klass = cool_conmin_gencan_parameters;	
+	rb_obj_reveal(ary, cool_conmin_gencan_parameters);	
 	return ary;
 }
 
--- /dev/null
+++ b/ext/porting.h
@@ -0,0 +1,5 @@
+#include <ruby/version.h>
+
+#if RUBY_API_VERSION_CODE < 20100
+  #define rb_obj_reveal(o,k) RBASIC(o)->klass = k
+#endif
--- a/ext/vector_complex.c
+++ b/ext/vector_complex.c
@@ -11,6 +11,7 @@
 #include "rb_gsl_config.h"
 #include "rb_gsl_array.h"
 #include "rb_gsl_complex.h"
+#include "porting.h"
 
 EXTERN VALUE cgsl_complex;
 static VALUE rb_gsl_vector_complex_inner_product(int argc, VALUE *argv, VALUE obj);
@@ -939,9 +940,9 @@ static VALUE rb_gsl_vector_complex_trans
 static VALUE rb_gsl_vector_complex_trans2(VALUE obj)
 {
   if (CLASS_OF(obj) == cgsl_vector_complex) 
-    RBASIC(obj)->klass = cgsl_vector_complex_col;
+    rb_obj_reveal(obj, cgsl_vector_complex_col);
   else if (CLASS_OF(obj) == cgsl_vector_complex_col) 
-    RBASIC(obj)->klass = cgsl_vector_complex;
+    rb_obj_reveal(obj, cgsl_vector_complex);
   else {
     rb_raise(rb_eRuntimeError, "method trans! for %s is forbidden",
 	     rb_class2name(CLASS_OF(obj)));
--- a/ext/vector_source.c
+++ b/ext/vector_source.c
@@ -36,6 +36,8 @@
 #define VEC_VIEW_P VECTOR_INT_VIEW_P
 #endif
 
+#include "porting.h"
+
 void FUNCTION(get_range,beg_en_n)(VALUE range, BASE *beg, BASE *en, size_t *n, int *step);
 
 void get_range_beg_en_n_for_size(VALUE range,
@@ -673,15 +675,15 @@ static VALUE FUNCTION(rb_gsl_vector,tran
 static VALUE FUNCTION(rb_gsl_vector,trans_bang)(VALUE obj)
 {
 #ifdef BASE_DOUBLE
-  if (CLASS_OF(obj) == cgsl_vector) RBASIC(obj)->klass = cgsl_vector_col;
-  else if (CLASS_OF(obj) == cgsl_vector_col) RBASIC(obj)->klass = cgsl_vector;
+  if (CLASS_OF(obj) == cgsl_vector) rb_obj_reveal(obj, cgsl_vector_col);
+  else if (CLASS_OF(obj) == cgsl_vector_col) rb_obj_reveal(obj, cgsl_vector);
   else {
     rb_raise(rb_eRuntimeError, "method trans! for %s is not permitted.",
 	     rb_class2name(CLASS_OF(obj)));
   }	
 #elif defined(BASE_INT)
-  if (CLASS_OF(obj) == cgsl_vector_int) RBASIC(obj)->klass = cgsl_vector_int_col;
-  else if (CLASS_OF(obj) == cgsl_vector_int_col) RBASIC(obj)->klass = cgsl_vector_int;
+  if (CLASS_OF(obj) == cgsl_vector_int) rb_obj_reveal(obj, cgsl_vector_int_col);
+  else if (CLASS_OF(obj) == cgsl_vector_int_col) rb_obj_reveal(obj, cgsl_vector_int);
   else {
     rb_raise(rb_eRuntimeError, "method trans! for %s is not permitted.",
 	     rb_class2name(CLASS_OF(obj)));