diff --git a/src/libnm-core-impl/nm-simple-connection.c b/src/libnm-core-impl/nm-simple-connection.c
index 6834c41e23..7b133e4551 100644
--- a/src/libnm-core-impl/nm-simple-connection.c
+++ b/src/libnm-core-impl/nm-simple-connection.c
@@ -20,6 +20,20 @@
 
 /*****************************************************************************/
 
+/**
+ * NMSimpleConnection:
+ */
+struct _NMSimpleConnection {
+    GObject parent;
+};
+
+struct _NMSimpleConnectionClass {
+    GObjectClass parent;
+
+    /* In the past, this struct was public API. Preserve ABI! */
+    gpointer padding[4];
+};
+
 static void nm_simple_connection_interface_init(NMConnectionInterface *iface);
 
 G_DEFINE_TYPE_WITH_CODE(NMSimpleConnection,
diff --git a/src/libnm-core-public/nm-simple-connection.h b/src/libnm-core-public/nm-simple-connection.h
index 38473b6287..6586c922d3 100644
--- a/src/libnm-core-public/nm-simple-connection.h
+++ b/src/libnm-core-public/nm-simple-connection.h
@@ -25,19 +25,7 @@ G_BEGIN_DECLS
 #define NM_SIMPLE_CONNECTION_GET_CLASS(obj) \
     (G_TYPE_INSTANCE_GET_CLASS((obj), NM_TYPE_SIMPLE_CONNECTION, NMSimpleConnectionClass))
 
-/**
- * NMSimpleConnection:
- */
-struct _NMSimpleConnection {
-    GObject parent;
-};
-
-typedef struct {
-    GObjectClass parent_class;
-
-    /*< private >*/
-    gpointer padding[4];
-} NMSimpleConnectionClass;
+typedef struct _NMSimpleConnectionClass NMSimpleConnectionClass;
 
 GType nm_simple_connection_get_type(void);