diff --git a/psycopg/adapter_datetime.c b/psycopg/adapter_datetime.c
index b2b0555e..98922d3c 100644
--- a/psycopg/adapter_datetime.c
+++ b/psycopg/adapter_datetime.c
@@ -38,14 +38,14 @@
 
 /* the pointer to the datetime module API is initialized by the module init
    code, we just need to grab it */
-extern PyObject* pyDateTimeModuleP;
-extern PyObject *pyDateTypeP;
-extern PyObject *pyTimeTypeP;
-extern PyObject *pyDateTimeTypeP;
-extern PyObject *pyDeltaTypeP;
+extern HIDDEN PyObject* pyDateTimeModuleP;
+extern HIDDEN PyObject *pyDateTypeP;
+extern HIDDEN PyObject *pyTimeTypeP;
+extern HIDDEN PyObject *pyDateTimeTypeP;
+extern HIDDEN PyObject *pyDeltaTypeP;
 
-extern PyObject *pyPsycopgTzModule;
-extern PyObject *pyPsycopgTzLOCAL;
+extern HIDDEN PyObject *pyPsycopgTzModule;
+extern HIDDEN PyObject *pyPsycopgTzLOCAL;
 
 /* datetime_str, datetime_getquoted - return result of quoting */
 
diff --git a/psycopg/adapter_mxdatetime.c b/psycopg/adapter_mxdatetime.c
index 797daf25..48ead92e 100644
--- a/psycopg/adapter_mxdatetime.c
+++ b/psycopg/adapter_mxdatetime.c
@@ -35,7 +35,7 @@
 
 /* the pointer to the mxDateTime API is initialized by the module init code,
    we just need to grab it */
-extern mxDateTimeModule_APIObject *mxDateTimeP;
+extern HIDDEN mxDateTimeModule_APIObject *mxDateTimeP;
 
 
 /* mxdatetime_str, mxdatetime_getquoted - return result of quoting */
diff --git a/psycopg/connection_int.c b/psycopg/connection_int.c
index c5ba1ece..aef2ec31 100644
--- a/psycopg/connection_int.c
+++ b/psycopg/connection_int.c
@@ -67,14 +67,14 @@ conn_connect(connectionObject *self)
 
     /* we need the initial date style to be ISO, for typecasters; if the user
        later change it, she must know what she's doing... */
-    const char datestyle[] = "SET DATESTYLE TO 'ISO'";
-    const char encoding[]  = "SHOW client_encoding";
-    const char isolevel[]  = "SHOW default_transaction_isolation";
+    static const char datestyle[] = "SET DATESTYLE TO 'ISO'";
+    static const char encoding[]  = "SHOW client_encoding";
+    static const char isolevel[]  = "SHOW default_transaction_isolation";
 
-    const char lvl1a[] = "read uncommitted";
-    const char lvl1b[] = "read committed";
-    const char lvl2a[] = "repeatable read";
-    const char lvl2b[] = "serializable";
+    static const char lvl1a[] = "read uncommitted";
+    static const char lvl1b[] = "read committed";
+    static const char lvl2a[] = "repeatable read";
+    static const char lvl2b[] = "serializable";
 
     Py_BEGIN_ALLOW_THREADS;
     pgconn = PQconnectdb(self->dsn);
diff --git a/psycopg/typecast_datetime.c b/psycopg/typecast_datetime.c
index 6748c6a6..99f4b608 100644
--- a/psycopg/typecast_datetime.c
+++ b/psycopg/typecast_datetime.c
@@ -25,11 +25,11 @@
 
 /* the pointer to the datetime module API is initialized by the module init
    code, we just need to grab it */
-extern PyObject* pyDateTimeModuleP;
-extern PyObject *pyDateTypeP;
-extern PyObject *pyTimeTypeP;
-extern PyObject *pyDateTimeTypeP;
-extern PyObject *pyDeltaTypeP;
+extern HIDDEN PyObject* pyDateTimeModuleP;
+extern HIDDEN PyObject *pyDateTypeP;
+extern HIDDEN PyObject *pyTimeTypeP;
+extern HIDDEN PyObject *pyDateTimeTypeP;
+extern HIDDEN PyObject *pyDeltaTypeP;
 
 /** DATE - cast a date into a date python object **/
 
diff --git a/psycopg/typecast_mxdatetime.c b/psycopg/typecast_mxdatetime.c
index bdd2955b..a6e9509e 100644
--- a/psycopg/typecast_mxdatetime.c
+++ b/psycopg/typecast_mxdatetime.c
@@ -23,7 +23,7 @@
 
 /* the pointer to the mxDateTime API is initialized by the module init code,
    we just need to grab it */
-extern mxDateTimeModule_APIObject *mxDateTimeP;
+extern HIDDEN mxDateTimeModule_APIObject *mxDateTimeP;
 
 /** DATE - cast a date into mx.DateTime python object **/