diff --git a/CHANGES b/CHANGES
index 0c1b86dcb..9a703e0ab 100644
--- a/CHANGES
+++ b/CHANGES
@@ -20,6 +20,7 @@ Misc:
  - SDL: Allow GBASDLAudio to be used without a thread context
  - All: Improved PowerPC support
  - All: Fix some undefined behavior warnings
+ - GBA Audio: Implement missing flags on SOUNDCNT_X register
 
 0.3.1: (2015-10-24)
 Bugfixes:
diff --git a/src/gba/audio.c b/src/gba/audio.c
index 305b4545b..c281e3552 100644
--- a/src/gba/audio.c
+++ b/src/gba/audio.c
@@ -283,6 +283,12 @@ int32_t GBAAudioProcessEvents(struct GBAAudio* audio, int32_t cycles) {
 					}
 				}
 			}
+
+			audio->p->memory.io[REG_SOUNDCNT_X >> 1] &= ~0x000F;
+			audio->p->memory.io[REG_SOUNDCNT_X >> 1] |= audio->playingCh1;
+			audio->p->memory.io[REG_SOUNDCNT_X >> 1] |= audio->playingCh2 << 1;
+			audio->p->memory.io[REG_SOUNDCNT_X >> 1] |= audio->playingCh3 << 2;
+			audio->p->memory.io[REG_SOUNDCNT_X >> 1] |= audio->playingCh4 << 2;
 		}
 
 		audio->nextSample -= audio->eventDiff;
diff --git a/src/gba/io.c b/src/gba/io.c
index 02652a238..f1f9a8d3c 100644
--- a/src/gba/io.c
+++ b/src/gba/io.c
@@ -351,6 +351,8 @@ void GBAIOWrite(struct GBA* gba, uint32_t address, uint16_t value) {
 			break;
 		case REG_SOUNDCNT_X:
 			GBAAudioWriteSOUNDCNT_X(&gba->audio, value);
+			value &= 0xFFFF;
+			value |= gba->memory.io[REG_SOUNDCNT_X >> 1] & 0xF;
 			break;
 		case REG_SOUNDBIAS:
 			GBAAudioWriteSOUNDBIAS(&gba->audio, value);