diff --git a/gio/gresource.c b/gio/gresource.c
index 26455c738..ad40a78ec 100644
--- a/gio/gresource.c
+++ b/gio/gresource.c
@@ -38,7 +38,7 @@ struct _GResource
   GvdbTable *table;
 };
 
-static void register_lazy_static_resources ();
+static void register_lazy_static_resources (void);
 
 G_DEFINE_BOXED_TYPE (GResource, g_resource, g_resource_ref, g_resource_unref)
 
diff --git a/gobject/tests/threadtests.c b/gobject/tests/threadtests.c
index eae7ec0ce..fd3322207 100644
--- a/gobject/tests/threadtests.c
+++ b/gobject/tests/threadtests.c
@@ -41,7 +41,7 @@ call_counter_init (gpointer tclass)
     }
 }
 
-static void interface_per_class_init () { call_counter_init (NULL); }
+static void interface_per_class_init (void) { call_counter_init (NULL); }
 
 /* define 3 test interfaces */
 typedef GTypeInterface MyFace0Interface;
diff --git a/tests/assert-msg-test.c b/tests/assert-msg-test.c
index 1dbe7bc15..44f8010ee 100644
--- a/tests/assert-msg-test.c
+++ b/tests/assert-msg-test.c
@@ -1,6 +1,6 @@
 #include <glib.h>
 
-int main()
+int main(int argc, char **argv)
 {
     g_assert(42 < 0);
     return 0;