diff --git a/src/apu/Gb_Oscs.cpp b/src/apu/Gb_Oscs.cpp
index 644f6ddd..bba510b5 100644
--- a/src/apu/Gb_Oscs.cpp
+++ b/src/apu/Gb_Oscs.cpp
@@ -116,7 +116,7 @@ int Gb_Wave::access( unsigned addr ) const
 	if ( enabled )
 	{
 		addr = phase & (bank_size - 1);
-		if ( mode == Gb_Apu::mode_dmg )
+		if ( mode == Gb_Apu::mode_agb )
 		{
 			addr++;
 			if ( delay > clk_mul )
@@ -442,7 +442,7 @@ static unsigned run_lfsr( unsigned s, unsigned mask, int count )
 	{
 		// won't fully replace upper 8 bits, so have to do the unoptimized way
 		while ( --count >= 0 )
-			s = (s >> 1 | mask) ^ (mask & -((s - 1) & 2));
+			s = (s >> 1 | mask) ^ (mask & (0 - ((s - 1) & 2)));
 	}
 	else
 	{