diff --git a/plugins/bit_invader/bit_invader.cpp b/plugins/bit_invader/bit_invader.cpp
index 5099db9e6..b01f34ed6 100644
--- a/plugins/bit_invader/bit_invader.cpp
+++ b/plugins/bit_invader/bit_invader.cpp
@@ -246,7 +246,7 @@ void bitInvader::normalize( void )
 	// analyze
 	float max = 0;
 	const float* samples = m_graph.samples();
-	for (unsigned int i=0; i < m_graph.length(); i++)
+	for(int i=0; i < m_graph.length(); i++)
 	{
 		if (fabsf(samples[i]) > max) { max = fabs(samples[i]); }
 	}
diff --git a/plugins/sf2_player/sf2_player.cpp b/plugins/sf2_player/sf2_player.cpp
index 3cfcf53a9..37befba99 100644
--- a/plugins/sf2_player/sf2_player.cpp
+++ b/plugins/sf2_player/sf2_player.cpp
@@ -105,7 +105,8 @@ sf2Instrument::sf2Instrument( instrumentTrack * _instrument_track ) :
 
 	m_settings = new_fluid_settings();
 
-	fluid_settings_setint( m_settings, "audio.period-size", engine::getMixer()->framesPerPeriod() );
+	fluid_settings_setint( m_settings, (char *) "audio.period-size",
+					engine::getMixer()->framesPerPeriod() );
 
 	// This is just our starting instance of synth.  It is recreated
 	// everytime we load a new soundfont.
@@ -409,9 +410,10 @@ void sf2Instrument::updateSampleRate( void )
 	double tempRate;
 	
 	// Set & get, returns the true sample rate
-	fluid_settings_setnum( m_settings, "synth.sample-rate",
+	fluid_settings_setnum( m_settings, (char *) "synth.sample-rate",
 				engine::getMixer()->processingSampleRate() );
-	fluid_settings_getnum( m_settings, "synth.sample-rate", &tempRate );
+	fluid_settings_getnum( m_settings, (char *) "synth.sample-rate",
+								&tempRate );
 	m_internalSampleRate = static_cast<int>( tempRate );
 
 	if( m_font )
diff --git a/plugins/spectrum_analyzer/spectrum_analyzer.cpp b/plugins/spectrum_analyzer/spectrum_analyzer.cpp
index 5b7c1405e..fda7a1bcb 100644
--- a/plugins/spectrum_analyzer/spectrum_analyzer.cpp
+++ b/plugins/spectrum_analyzer/spectrum_analyzer.cpp
@@ -282,16 +282,14 @@ static const int onethirdoctavecenterfr[] = {20, 25, 31, 40, 50, 63, 80, 100, 12
       returns power on success, else -1          */
 float signalpower(float *timesignal, int num_values)
 {
-	float power=0;
-	unsigned int i;
-	
 	if ( num_values<=0 )
 		return -1;
 
 	if( timesignal==NULL )
 		return -1;
 		
-	for ( i=0; i<num_values; i++ )	
+	float power=0;
+	for ( int i=0; i<num_values; i++ )	
 	{
 		power+=timesignal[i]*timesignal[i];
 	}