diff --git a/libguile/goops.c b/libguile/goops.c
index a6923354f..51b9b4201 100644
--- a/libguile/goops.c
+++ b/libguile/goops.c
@@ -158,7 +158,12 @@ SCM scm_class_protected_opaque, scm_class_protected_read_only;
 SCM scm_class_scm;
 SCM scm_class_int, scm_class_float, scm_class_double;
 
-SCM *scm_port_class = 0;
+/* Port classes.  Allocate 3 times the maximum number of port types so that
+   input ports, output ports, and in/out ports can be stored at different
+   offsets.  See `SCM_IN_PCLASS_INDEX' et al.  */
+SCM scm_port_class[3 * SCM_I_MAX_PORT_TYPE_COUNT];
+
+/* SMOB classes.  */
 SCM scm_smob_class[SCM_I_MAX_SMOB_TYPE_COUNT];
 
 SCM scm_no_applicable_method;
@@ -2771,11 +2776,6 @@ create_port_classes (void)
 {
   long i;
 
-  /* Allocate 3 times the maximum number of port types so that input ports,
-     output ports, and in/out ports can be stored at different offsets.  See
-     `SCM_IN_PCLASS_INDEX' et al.  */
-  scm_port_class = scm_calloc (3 * SCM_I_MAX_PORT_TYPE_COUNT * sizeof (SCM));
-
   for (i = 0; i < scm_numptob; ++i)
     scm_make_port_classes (i, SCM_PTOBNAME (i));
 }
diff --git a/libguile/goops.h b/libguile/goops.h
index 7ca276ff4..d43d73642 100644
--- a/libguile/goops.h
+++ b/libguile/goops.h
@@ -170,7 +170,7 @@ SCM_API SCM scm_class_complex;
 SCM_API SCM scm_class_integer;
 SCM_API SCM scm_class_fraction;
 SCM_API SCM scm_class_unknown;
-SCM_API SCM *scm_port_class;
+SCM_API SCM scm_port_class[];
 SCM_API SCM scm_smob_class[];
 SCM_API SCM scm_class_top;
 SCM_API SCM scm_class_object;
diff --git a/libguile/ports.c b/libguile/ports.c
index dc412a445..1f49708c8 100644
--- a/libguile/ports.c
+++ b/libguile/ports.c
@@ -172,7 +172,7 @@ scm_make_port_type (char *name,
       scm_memory_error ("scm_make_port_type");
     }
   /* Make a class object if Goops is present */
-  if (scm_port_class)
+  if (SCM_UNPACK (scm_port_class[0]) != 0)
     scm_make_port_classes (scm_numptob - 1, SCM_PTOBNAME (scm_numptob - 1));
   return scm_tc7_port + (scm_numptob - 1) * 256;
 }