diff --git a/ac108.c b/ac108.c
index cd20547..8c09143 100644
--- a/ac108.c
+++ b/ac108.c
@@ -865,6 +865,7 @@ static int ac108_set_fmt(struct snd_soc_dai *dai, unsigned int fmt) {
 			/* TODO: Both cpu_dai and codec_dai(AC108) be set as slave in DTS */
 			dev_dbg(dai->dev, "used as slave when AC101 is master\n");
 		}
+		fallthrough;
 	case SND_SOC_DAIFMT_CBS_CFS:    /*AC108 Slave*/
 		dev_dbg(dai->dev, "AC108 set to work as Slave\n");
 		/**
diff --git a/sound-compatible-4.18.h b/sound-compatible-4.18.h
index dc5a787..faed848 100644
--- a/sound-compatible-4.18.h
+++ b/sound-compatible-4.18.h
@@ -15,6 +15,14 @@
 #define __NO_SND_SOC_CODEC_DRV     0
 #endif
 
+#if LINUX_VERSION_CODE < KERNEL_VERSION(5,4,0)
+#if __has_attribute(__fallthrough__)
+# define fallthrough                    __attribute__((__fallthrough__))
+#else
+# define fallthrough                    do {} while (0)  /* fallthrough */
+#endif
+#endif
+
 #if __NO_SND_SOC_CODEC_DRV
 #define codec                      component
 #define snd_soc_codec              snd_soc_component
diff --git a/wm8960.c b/wm8960.c
index f26f59b..34d4dad 100644
--- a/wm8960.c
+++ b/wm8960.c
@@ -753,6 +753,7 @@ static int wm8960_hw_params(struct snd_pcm_substream *substream,
 			iface |= 0x000c;
 			break;
 		}
+		fallthrough;
 	default:
 		dev_err(codec->dev, "unsupported width %d\n",
 			params_width(params));