diff --git a/linker_scripts/us/symbol_addrs_code.txt b/linker_scripts/us/symbol_addrs_code.txt
index cc7996a..d16600f 100644
--- a/linker_scripts/us/symbol_addrs_code.txt
+++ b/linker_scripts/us/symbol_addrs_code.txt
@@ -1468,7 +1468,7 @@ n_alSynAllocFX = 0x8004FDA0; // type:func
 func_8004FE00 = 0x8004FE00; // type:func
 func_8004FF20 = 0x8004FF20; // type:func
 n_alSynStartVoiceParams = 0x8004FF40; // type:func
-func_80050020 = 0x80050020; // type:func
+n_alSynFreeVoice = 0x80050020; // type:func
 n_alFxPull = 0x800500C0; // type:func
 n_alFxParamHdl = 0x800503A0; // type:func
 _n_loadOutputBuffer = 0x80050600; // type:func
diff --git a/src/50C20.c b/src/50C20.c
deleted file mode 100644
index 8ba3e0e..0000000
--- a/src/50C20.c
+++ /dev/null
@@ -1,3 +0,0 @@
-#include "global.h"
-
-#pragma GLOBAL_ASM("asm/us/nonmatchings/50C20/func_80050020.s")
diff --git a/src/libnaudio/n_synfreevoice.c b/src/libnaudio/n_synfreevoice.c
new file mode 100644
index 0000000..0445d13
--- /dev/null
+++ b/src/libnaudio/n_synfreevoice.c
@@ -0,0 +1,52 @@
+/*====================================================================
+ *
+ * Copyright 1993, Silicon Graphics, Inc.
+ * All Rights Reserved.
+ *
+ * This is UNPUBLISHED PROPRIETARY SOURCE CODE of Silicon Graphics,
+ * Inc.; the contents of this file may not be disclosed to third
+ * parties, copied or duplicated in any form, in whole or in part,
+ * without the prior written permission of Silicon Graphics, Inc.
+ *
+ * RESTRICTED RIGHTS LEGEND:
+ * Use, duplication or disclosure by the Government is subject to
+ * restrictions as set forth in subdivision (c)(1)(ii) of the Rights
+ * in Technical Data and Computer Software clause at DFARS
+ * 252.227-7013, and/or in similar or successor clauses in the FAR,
+ * DOD or NASA FAR Supplement. Unpublished - rights reserved under the
+ * Copyright Laws of the United States.
+ *====================================================================*/
+#include <ultraerror.h>
+#include <os_internal.h>
+
+#include <os.h>
+#include "n_synthInternals.h"
+
+void n_alSynFreeVoice(N_ALVoice *voice)
+{
+    ALFilter *f;
+    N_ALFreeParam *update;
+
+    if (voice->pvoice) {
+        if (voice->pvoice->offset) { /* if voice was stolen */
+            update = (N_ALFreeParam *)__n_allocParam();
+            ALFailIf(update == 0, ERR_ALSYN_NO_UPDATE);
+
+            /*
+             * set voice data
+             */
+#ifdef SAMPLE_ROUND
+	      update->delta  = SAMPLE184( n_syn->paramSamples + voice->pvoice->offset);
+#else
+            update->delta  = n_syn->paramSamples + voice->pvoice->offset;
+#endif
+            update->type   = AL_FILTER_FREE_VOICE;
+            update->pvoice = voice->pvoice;
+
+	    n_alEnvmixerParam(voice->pvoice, AL_FILTER_ADD_UPDATE, update); 
+        } else {
+            _n_freePVoice(voice->pvoice);
+        }
+        voice->pvoice = 0;
+    }
+}
diff --git a/yamls/us/rom.yaml b/yamls/us/rom.yaml
index 8850f50..cc7a4ac 100644
--- a/yamls/us/rom.yaml
+++ b/yamls/us/rom.yaml
@@ -116,7 +116,7 @@
     - [0x509A0, c, libnaudio/n_synallocfx]
     - [0x50A00, c]
     - [0x50B40, c, libnaudio/n_synstartvoiceparam]
-    - [0x50C20, c]
+    - [0x50C20, c, libnaudio/n_synfreevoice]
     - [0x50CC0, c, libnaudio/n_reverb]
     - [0x51740, c]
     - [0x517A0, c] # yay0 audio decoder