diff --git a/configure.ac b/configure.ac
index f0f6962a..e8316158 100644
--- a/configure.ac
+++ b/configure.ac
@@ -461,6 +461,16 @@ AC_CHECK_LIB(m,atan2,[AC_DEFINE(HAVE_ATAN2,1,[have atan2() in libm.])])
 PKG_CHECK_MODULES(REQUIRED, glib-2.0 >= 2.6 gmodule-2.0 gobject-2.0)
 PACKAGES_USED="$PACKAGES_USED glib-2.0 gmodule-2.0 gobject-2.0"
 
+# from 2.12 we have g_base64_encode()
+PKG_CHECK_MODULES(BASE64_ENCODE, glib-2.0 >= 2.12,
+  [AC_DEFINE(HAVE_BASE64_ENCODE,1,
+	    [define if your glib has g_base64_encode().]
+   )
+  ],
+  [:
+  ]
+)
+
 # from 2.14 we have g_option_context_get_help()
 PKG_CHECK_MODULES(CONTEXT_GET_HELP, glib-2.0 >= 2.14,
   [AC_DEFINE(HAVE_CONTEXT_GET_HELP,1,
diff --git a/libvips/iofuncs/base64.c b/libvips/iofuncs/base64.c
index 8398ff30..fe9dc2cf 100644
--- a/libvips/iofuncs/base64.c
+++ b/libvips/iofuncs/base64.c
@@ -90,6 +90,24 @@ Modified on:
 #include <vips/vips.h>
 #include <vips/internal.h>
 
+#ifdef HAVE_BASE64_ENCODE
+
+/* glib 2.12 adds these.
+ */
+char *
+vips__b64_encode( const unsigned char *data, size_t data_length )
+{
+	return( g_base64_encode( data, data_length ) );
+}
+
+unsigned char *
+vips__b64_decode( const char *buffer, size_t *data_length )
+{
+	return( g_base64_decode( buffer, data_length ) );
+}
+
+#else /*!HAVE_BASE64_ENCODE*/
+
 static unsigned char b64_list[] =
 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
 
@@ -295,3 +313,5 @@ vips__b64_decode( const char *buffer, size_t *data_length )
 
 	return( data );
 }
+
+#endif /*HAVE_BASE64_ENCODE*/