diff --git a/src/i_oalsound.c b/src/i_oalsound.c
index bfd7da4d..71ba7500 100644
--- a/src/i_oalsound.c
+++ b/src/i_oalsound.c
@@ -589,7 +589,7 @@ boolean I_OAL_CacheSound(sfxinfo_t *sfx)
         lumplen = W_LumpLength(lumpnum);
 
         // Check the header, and ensure this is a valid sound
-        if (lumpdata[0] == 0x03 && lumpdata[1] == 0x00)
+        if (lumplen > DMXHDRSIZE && lumpdata[0] == 0x03 && lumpdata[1] == 0x00)
         {
             freq = (lumpdata[3] <<  8) |  lumpdata[2];
             size = (lumpdata[7] << 24) | (lumpdata[6] << 16) |