diff --git a/src/engine/platform/sound/namco.cpp b/src/engine/platform/sound/namco.cpp
index 3602137bd..2ab304626 100644
--- a/src/engine/platform/sound/namco.cpp
+++ b/src/engine/platform/sound/namco.cpp
@@ -388,6 +388,8 @@ void namco_device::polepos_sound_w(int offset, uint8_t data)
 
 	case 0x23:
 		voice->waveform_select = data & 7;
+		// https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html#index-Wimplicit-fallthrough
+		// fall through
 	case 0x02:
 	case 0x03:
 		voice->volume[0] = voice->volume[1] = 0;
@@ -469,6 +471,8 @@ void namco_15xx_device::namco_15xx_w(int offset, uint8_t data)
 
 	case 0x06:
 		voice->waveform_select = (data >> 4) & 7;
+		// https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html#index-Wimplicit-fallthrough
+		// fall through
 	case 0x04:
 	case 0x05:
 		/* the frequency has 20 bits */
@@ -542,6 +546,8 @@ void namco_cus30_device::namcos1_sound_w(int offset, uint8_t data)
 
 	case 0x01:
 		voice->waveform_select = (data >> 4) & 15;
+		// https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html#index-Wimplicit-fallthrough
+		// fall through
 	case 0x02:
 	case 0x03:
 		/* the frequency has 20 bits */