diff --git a/libfwupd/fwupd-client-sync.c b/libfwupd/fwupd-client-sync.c
index 0342fe657..c88960fd0 100644
--- a/libfwupd/fwupd-client-sync.c
+++ b/libfwupd/fwupd-client-sync.c
@@ -1892,6 +1892,11 @@ fwupd_client_set_approved_firmware(FwupdClient *self,
 	g_autoptr(FwupdClientHelper) helper = NULL;
 	g_autoptr(GPtrArray) array = g_ptr_array_new_with_free_func(g_free);
 
+	g_return_val_if_fail(FWUPD_IS_CLIENT(self), FALSE);
+	g_return_val_if_fail(checksums != NULL, FALSE);
+	g_return_val_if_fail(cancellable == NULL || G_IS_CANCELLABLE(cancellable), FALSE);
+	g_return_val_if_fail(error == NULL || *error == NULL, FALSE);
+
 	/* connect */
 	if (!fwupd_client_connect(self, cancellable, error))
 		return FALSE;
@@ -2288,6 +2293,7 @@ fwupd_client_upload_bytes(FwupdClient *self,
 
 	g_return_val_if_fail(FWUPD_IS_CLIENT(self), NULL);
 	g_return_val_if_fail(url != NULL, NULL);
+	g_return_val_if_fail(payload != NULL, NULL);
 	g_return_val_if_fail(cancellable == NULL || G_IS_CANCELLABLE(cancellable), NULL);
 	g_return_val_if_fail(error == NULL || *error == NULL, NULL);
 
diff --git a/libfwupd/fwupd-client.c b/libfwupd/fwupd-client.c
index afd5619e5..03462d873 100644
--- a/libfwupd/fwupd-client.c
+++ b/libfwupd/fwupd-client.c
@@ -4896,6 +4896,7 @@ fwupd_client_upload_bytes_async(FwupdClient *self,
 
 	g_return_if_fail(FWUPD_IS_CLIENT(self));
 	g_return_if_fail(url != NULL);
+	g_return_if_fail(payload != NULL);
 	g_return_if_fail(cancellable == NULL || G_IS_CANCELLABLE(cancellable));
 	g_return_if_fail(priv->proxy != NULL);
 
diff --git a/libfwupd/fwupd-common.c b/libfwupd/fwupd-common.c
index 4e0d28ce9..ed1051b19 100644
--- a/libfwupd/fwupd-common.c
+++ b/libfwupd/fwupd-common.c
@@ -106,6 +106,7 @@ fwupd_checksum_format_for_display(const gchar *checksum)
 const gchar *
 fwupd_checksum_get_by_kind(GPtrArray *checksums, GChecksumType kind)
 {
+	g_return_val_if_fail(checksums != NULL, NULL);
 	for (guint i = 0; i < checksums->len; i++) {
 		const gchar *checksum = g_ptr_array_index(checksums, i);
 		if (fwupd_checksum_guess_kind(checksum) == kind)
@@ -128,6 +129,7 @@ const gchar *
 fwupd_checksum_get_best(GPtrArray *checksums)
 {
 	GChecksumType checksum_types[] = {G_CHECKSUM_SHA512, G_CHECKSUM_SHA256, G_CHECKSUM_SHA1, 0};
+	g_return_val_if_fail(checksums != NULL, NULL);
 	for (guint i = 0; checksum_types[i] != 0; i++) {
 		for (guint j = 0; j < checksums->len; j++) {
 			const gchar *checksum = g_ptr_array_index(checksums, j);
@@ -309,6 +311,9 @@ fwupd_build_user_agent(const gchar *package_name, const gchar *package_version)
 	GString *str = g_string_new(NULL);
 	g_autofree gchar *system = NULL;
 
+	g_return_val_if_fail(package_name != NULL, NULL);
+	g_return_val_if_fail(package_version != NULL, NULL);
+
 	/* application name and version */
 	g_string_append_printf(str, "%s/%s", package_name, package_version);
 
diff --git a/libfwupd/fwupd-device.c b/libfwupd/fwupd-device.c
index dc40b2383..03ab314ce 100644
--- a/libfwupd/fwupd-device.c
+++ b/libfwupd/fwupd-device.c
@@ -1601,6 +1601,9 @@ fwupd_device_incorporate(FwupdDevice *self, FwupdDevice *donor)
 	FwupdDevicePrivate *priv = GET_PRIVATE(self);
 	FwupdDevicePrivate *priv_donor = GET_PRIVATE(donor);
 
+	g_return_if_fail(FWUPD_IS_DEVICE(self));
+	g_return_if_fail(FWUPD_IS_DEVICE(donor));
+
 	fwupd_device_add_flag(self, priv_donor->flags);
 	if (priv->created == 0)
 		fwupd_device_set_created(self, priv_donor->created);
@@ -2518,6 +2521,7 @@ fwupd_device_add_release(FwupdDevice *self, FwupdRelease *release)
 {
 	FwupdDevicePrivate *priv = GET_PRIVATE(self);
 	g_return_if_fail(FWUPD_IS_DEVICE(self));
+	g_return_if_fail(FWUPD_IS_RELEASE(release));
 	g_ptr_array_add(priv->releases, g_object_ref(release));
 }
 
@@ -3257,6 +3261,8 @@ fwupd_device_array_from_variant(GVariant *value)
 	gsize sz;
 	g_autoptr(GVariant) untuple = NULL;
 
+	g_return_val_if_fail(value != NULL, NULL);
+
 	array = g_ptr_array_new_with_free_func((GDestroyNotify)g_object_unref);
 	untuple = g_variant_get_child_value(value, 0);
 	sz = g_variant_n_children(untuple);
diff --git a/libfwupd/fwupd-plugin.c b/libfwupd/fwupd-plugin.c
index f92a2738e..17bb56c0f 100644
--- a/libfwupd/fwupd-plugin.c
+++ b/libfwupd/fwupd-plugin.c
@@ -458,6 +458,8 @@ fwupd_plugin_array_from_variant(GVariant *value)
 	gsize sz;
 	g_autoptr(GVariant) untuple = NULL;
 
+	g_return_val_if_fail(value != NULL, NULL);
+
 	array = g_ptr_array_new_with_free_func((GDestroyNotify)g_object_unref);
 	untuple = g_variant_get_child_value(value, 0);
 	sz = g_variant_n_children(untuple);
diff --git a/libfwupd/fwupd-release.c b/libfwupd/fwupd-release.c
index 71966cff1..65b3d0e75 100644
--- a/libfwupd/fwupd-release.c
+++ b/libfwupd/fwupd-release.c
@@ -2318,6 +2318,8 @@ fwupd_release_array_from_variant(GVariant *value)
 	gsize sz;
 	g_autoptr(GVariant) untuple = NULL;
 
+	g_return_val_if_fail(value != NULL, NULL);
+
 	array = g_ptr_array_new_with_free_func((GDestroyNotify)g_object_unref);
 	untuple = g_variant_get_child_value(value, 0);
 	sz = g_variant_n_children(untuple);
diff --git a/libfwupd/fwupd-remote.c b/libfwupd/fwupd-remote.c
index c9c1ca374..ba6690846 100644
--- a/libfwupd/fwupd-remote.c
+++ b/libfwupd/fwupd-remote.c
@@ -1766,6 +1766,8 @@ fwupd_remote_array_from_variant(GVariant *value)
 	gsize sz;
 	g_autoptr(GVariant) untuple = NULL;
 
+	g_return_val_if_fail(value != NULL, NULL);
+
 	remotes = g_ptr_array_new_with_free_func((GDestroyNotify)g_object_unref);
 	untuple = g_variant_get_child_value(value, 0);
 	sz = g_variant_n_children(untuple);
diff --git a/libfwupd/fwupd-request.c b/libfwupd/fwupd-request.c
index b6c910c26..886467351 100644
--- a/libfwupd/fwupd-request.c
+++ b/libfwupd/fwupd-request.c
@@ -619,6 +619,8 @@ fwupd_request_from_variant(GVariant *value)
 	const gchar *type_string;
 	g_autoptr(GVariantIter) iter = NULL;
 
+	g_return_val_if_fail(value != NULL, NULL);
+
 	/* format from GetDetails */
 	type_string = g_variant_get_type_string(value);
 	if (g_strcmp0(type_string, "(a{sv})") == 0) {
diff --git a/libfwupd/fwupd-security-attr.c b/libfwupd/fwupd-security-attr.c
index 0dba11db0..4feb65472 100644
--- a/libfwupd/fwupd-security-attr.c
+++ b/libfwupd/fwupd-security-attr.c
@@ -1268,6 +1268,8 @@ fwupd_security_attr_from_variant(GVariant *value)
 	const gchar *type_string;
 	g_autoptr(GVariantIter) iter = NULL;
 
+	g_return_val_if_fail(value != NULL, NULL);
+
 	type_string = g_variant_get_type_string(value);
 	if (g_strcmp0(type_string, "(a{sv})") == 0) {
 		rel = fwupd_security_attr_new(NULL);