diff --git a/gobject/glib-genmarshal.in b/gobject/glib-genmarshal.in
index 907957b4c..ed6de0ae8 100755
--- a/gobject/glib-genmarshal.in
+++ b/gobject/glib-genmarshal.in
@@ -556,7 +556,7 @@ def generate_prototype(retval, params,
                        va_marshal=False):
     '''Generate a marshaller declaration with the given @visibility. If @va_marshal
     is True, the marshaller will use variadic arguments in place of a GValue array.'''
-    signature = []
+    signature = ['G_BEGIN_DECLS']
 
     if visibility == Visibility.INTERNAL:
         signature += ['G_GNUC_INTERNAL']
@@ -585,6 +585,8 @@ def generate_prototype(retval, params,
         signature += [indent('int       n_params,', level=width, fill=' ')]
         signature += [indent('GType    *param_types);', level=width, fill=' ')]
 
+    signature += ['G_END_DECLS']
+
     return signature