diff --git a/gfx/filters/blargg_ntsc_snes_composite.c b/gfx/filters/blargg_ntsc_snes_composite.c
index 761ea5358d..d9bb63b25f 100755
--- a/gfx/filters/blargg_ntsc_snes_composite.c
+++ b/gfx/filters/blargg_ntsc_snes_composite.c
@@ -24,13 +24,9 @@
 #include "snes_ntsc/snes_ntsc.h"
 #include "snes_ntsc/snes_ntsc.c"
 
-void filter_size(unsigned*, unsigned*);
-void filter_render(uint32_t*, uint32_t*, unsigned, const uint16_t*, unsigned, unsigned, unsigned);
-
-struct snes_ntsc_t *ntsc;
-snes_ntsc_setup_t setup;
-int burst;
-int burst_toggle;
+static struct snes_ntsc_t *ntsc_composite;
+static int burst_composite;
+static int burst_toggle_composite;
 
 static unsigned blargg_ntsc_snes_composite_generic_input_fmts(void)
 {
@@ -70,24 +66,25 @@ static void *blargg_ntsc_snes_composite_generic_create(unsigned in_fmt, unsigned
 
 static void blargg_ntsc_snes_composite_initialize(void)
 {
+   snes_ntsc_setup_t setup;
    static bool initialized = false;
    if(initialized == true)
       return;
    initialized = true;
 
-   ntsc = (snes_ntsc_t*)malloc(sizeof *ntsc);
+   ntsc_composite = (snes_ntsc_t*)malloc(sizeof(*ntsc_composite));
    setup = snes_ntsc_composite;
    setup.merge_fields = 1;
-   snes_ntsc_init(ntsc, &setup);
+   snes_ntsc_init(ntsc_composite, &setup);
 
-   burst = 0;
-   burst_toggle = (setup.merge_fields ? 0 : 1);
+   burst_composite = 0;
+   burst_toggle_composite = (setup.merge_fields ? 0 : 1);
 }
 
 void terminate(void)
 {
-   if(ntsc)
-      free(ntsc);
+   if(ntsc_composite)
+      free(ntsc_composite);
 }
 
 static void blargg_ntsc_snes_composite_generic_output(void *data, unsigned *out_width, unsigned *out_height,
@@ -110,15 +107,15 @@ static void blargg_ntsc_snes_composite_render_rgb565(int width, int height,
       uint16_t *input, int pitch, uint16_t *output, int outpitch)
 {
    blargg_ntsc_snes_composite_initialize();
-   if(!ntsc)
+   if(!ntsc_composite)
       return;
 
    if(width <= 256)
-      snes_ntsc_blit(ntsc, input, pitch, burst, width, height, output, outpitch * 2, first, last);
+      snes_ntsc_blit(ntsc_composite, input, pitch, burst_composite, width, height, output, outpitch * 2, first, last);
    else
-      snes_ntsc_blit_hires(ntsc, input, pitch, burst, width, height, output, outpitch * 2, first, last);
+      snes_ntsc_blit_hires(ntsc_composite, input, pitch, burst_composite, width, height, output, outpitch * 2, first, last);
 
-   burst ^= burst_toggle;
+   burst_composite ^= burst_toggle_composite;
 }
 
 static void blargg_ntsc_snes_composite_rgb565(unsigned width, unsigned height,
diff --git a/gfx/filters/blargg_ntsc_snes_rf.c b/gfx/filters/blargg_ntsc_snes_rf.c
index 6f92318535..3f368dd5dc 100755
--- a/gfx/filters/blargg_ntsc_snes_rf.c
+++ b/gfx/filters/blargg_ntsc_snes_rf.c
@@ -24,13 +24,9 @@
 #include "snes_ntsc/snes_ntsc.h"
 #include "snes_ntsc/snes_ntsc.c"
 
-void filter_size(unsigned*, unsigned*);
-void filter_render(uint32_t*, uint32_t*, unsigned, const uint16_t*, unsigned, unsigned, unsigned);
-
-struct snes_ntsc_t *ntsc;
-snes_ntsc_setup_t setup;
-int burst;
-int burst_toggle;
+static struct snes_ntsc_t *ntsc_rf;
+static int burst_rf;
+static int burst_toggle_rf;
 
 static unsigned blargg_ntsc_snes_rf_generic_input_fmts(void)
 {
@@ -70,24 +66,25 @@ static void *blargg_ntsc_snes_rf_generic_create(unsigned in_fmt, unsigned out_fm
 
 static void blargg_ntsc_snes_rf_initialize(void)
 {
+   snes_ntsc_setup_t setup;
    static bool initialized = false;
    if(initialized == true)
       return;
    initialized = true;
 
-   ntsc = (snes_ntsc_t*)malloc(sizeof *ntsc);
+   ntsc_rf = (snes_ntsc_t*)malloc(sizeof(*ntsc_rf));
    setup = snes_ntsc_composite;
    setup.merge_fields = 0;
-   snes_ntsc_init(ntsc, &setup);
+   snes_ntsc_init(ntsc_rf, &setup);
 
-   burst = 0;
-   burst_toggle = (setup.merge_fields ? 0 : 1);
+   burst_rf = 0;
+   burst_toggle_rf = (setup.merge_fields ? 0 : 1);
 }
 
 void terminate(void)
 {
-   if(ntsc)
-      free(ntsc);
+   if(ntsc_rf)
+      free(ntsc_rf);
 }
 
 static void blargg_ntsc_snes_rf_generic_output(void *data, unsigned *out_width, unsigned *out_height,
@@ -110,15 +107,15 @@ static void blargg_ntsc_snes_rf_render_rgb565(int width, int height,
       uint16_t *input, int pitch, uint16_t *output, int outpitch)
 {
    blargg_ntsc_snes_rf_initialize();
-   if(!ntsc)
+   if(!ntsc_rf)
       return;
 
    if(width <= 256)
-      snes_ntsc_blit(ntsc, input, pitch, burst, width, height, output, outpitch * 2, first, last);
+      snes_ntsc_blit(ntsc_rf, input, pitch, burst_rf, width, height, output, outpitch * 2, first, last);
    else
-      snes_ntsc_blit_hires(ntsc, input, pitch, burst, width, height, output, outpitch * 2, first, last);
+      snes_ntsc_blit_hires(ntsc_rf, input, pitch, burst_rf, width, height, output, outpitch * 2, first, last);
 
-   burst ^= burst_toggle;
+   burst_rf ^= burst_toggle_rf;
 }
 
 static void blargg_ntsc_snes_rf_rgb565(unsigned width, unsigned height,
diff --git a/gfx/filters/blargg_ntsc_snes_rgb.c b/gfx/filters/blargg_ntsc_snes_rgb.c
index 2ab9a001d9..de0a9ce066 100755
--- a/gfx/filters/blargg_ntsc_snes_rgb.c
+++ b/gfx/filters/blargg_ntsc_snes_rgb.c
@@ -24,13 +24,9 @@
 #include "snes_ntsc/snes_ntsc.h"
 #include "snes_ntsc/snes_ntsc.c"
 
-void filter_size(unsigned*, unsigned*);
-void filter_render(uint32_t*, uint32_t*, unsigned, const uint16_t*, unsigned, unsigned, unsigned);
-
-struct snes_ntsc_t *ntsc;
-snes_ntsc_setup_t setup;
-int burst;
-int burst_toggle;
+static struct snes_ntsc_t *ntsc_rgb;
+static int burst_rgb;
+static int burst_toggle_rgb;
 
 static unsigned blargg_ntsc_snes_rgb_generic_input_fmts(void)
 {
@@ -70,24 +66,25 @@ static void *blargg_ntsc_snes_rgb_generic_create(unsigned in_fmt, unsigned out_f
 
 static void blargg_ntsc_snes_rgb_initialize(void)
 {
+   snes_ntsc_setup_t setup;
    static bool initialized = false;
    if(initialized == true)
       return;
    initialized = true;
 
-   ntsc = (snes_ntsc_t*)malloc(sizeof *ntsc);
+   ntsc_rgb = (snes_ntsc_t*)malloc(sizeof(*ntsc_rgb));
    setup = snes_ntsc_rgb;
    setup.merge_fields = 1;
-   snes_ntsc_init(ntsc, &setup);
+   snes_ntsc_init(ntsc_rgb, &setup);
 
-   burst = 0;
-   burst_toggle = (setup.merge_fields ? 0 : 1);
+   burst_rgb = 0;
+   burst_toggle_rgb = (setup.merge_fields ? 0 : 1);
 }
 
 void terminate(void)
 {
-   if(ntsc)
-      free(ntsc);
+   if(ntsc_rgb)
+      free(ntsc_rgb);
 }
 
 static void blargg_ntsc_snes_rgb_generic_output(void *data, unsigned *out_width, unsigned *out_height,
@@ -110,15 +107,15 @@ static void blargg_ntsc_snes_rgb_render_rgb565(int width, int height,
       uint16_t *input, int pitch, uint16_t *output, int outpitch)
 {
    blargg_ntsc_snes_rgb_initialize();
-   if(!ntsc)
+   if(!ntsc_rgb)
       return;
 
    if(width <= 256)
-      snes_ntsc_blit(ntsc, input, pitch, burst, width, height, output, outpitch * 2, first, last);
+      snes_ntsc_blit(ntsc_rgb, input, pitch, burst_rgb, width, height, output, outpitch * 2, first, last);
    else
-      snes_ntsc_blit_hires(ntsc, input, pitch, burst, width, height, output, outpitch * 2, first, last);
+      snes_ntsc_blit_hires(ntsc_rgb, input, pitch, burst_rgb, width, height, output, outpitch * 2, first, last);
 
-   burst ^= burst_toggle;
+   burst_rgb ^= burst_toggle_rgb;
 }
 
 static void blargg_ntsc_snes_rgb_rgb565(unsigned width, unsigned height,
diff --git a/gfx/filters/blargg_ntsc_snes_svideo.c b/gfx/filters/blargg_ntsc_snes_svideo.c
index a5aaee5a42..3b9154c49b 100755
--- a/gfx/filters/blargg_ntsc_snes_svideo.c
+++ b/gfx/filters/blargg_ntsc_snes_svideo.c
@@ -24,13 +24,9 @@
 #include "snes_ntsc/snes_ntsc.h"
 #include "snes_ntsc/snes_ntsc.c"
 
-void filter_size(unsigned*, unsigned*);
-void filter_render(uint32_t*, uint32_t*, unsigned, const uint16_t*, unsigned, unsigned, unsigned);
-
-struct snes_ntsc_t *ntsc;
-snes_ntsc_setup_t setup;
-int burst;
-int burst_toggle;
+static struct snes_ntsc_t *ntsc_svideo;
+static int burst_svideo;
+static int burst_toggle_svideo;
 
 static unsigned blargg_ntsc_snes_svideo_generic_input_fmts(void)
 {
@@ -70,24 +66,25 @@ static void *blargg_ntsc_snes_svideo_generic_create(unsigned in_fmt, unsigned ou
 
 static void blargg_ntsc_snes_svideo_initialize(void)
 {
+   snes_ntsc_setup_t setup;
    static bool initialized = false;
    if(initialized == true)
       return;
    initialized = true;
 
-   ntsc = (snes_ntsc_t*)malloc(sizeof *ntsc);
+   ntsc_svideo = (snes_ntsc_t*)malloc(sizeof(*ntsc_svideo));
    setup = snes_ntsc_svideo;
    setup.merge_fields = 1;
-   snes_ntsc_init(ntsc, &setup);
+   snes_ntsc_init(ntsc_svideo, &setup);
 
-   burst = 0;
-   burst_toggle = (setup.merge_fields ? 0 : 1);
+   burst_svideo = 0;
+   burst_toggle_svideo = (setup.merge_fields ? 0 : 1);
 }
 
 void terminate(void)
 {
-   if(ntsc)
-      free(ntsc);
+   if(ntsc_svideo)
+      free(ntsc_svideo);
 }
 
 static void blargg_ntsc_snes_svideo_generic_output(void *data, unsigned *out_width, unsigned *out_height,
@@ -110,15 +107,15 @@ static void blargg_ntsc_snes_svideo_render_rgb565(int width, int height,
       uint16_t *input, int pitch, uint16_t *output, int outpitch)
 {
    blargg_ntsc_snes_svideo_initialize();
-   if(!ntsc)
+   if(!ntsc_svideo)
       return;
 
    if(width <= 256)
-      snes_ntsc_blit(ntsc, input, pitch, burst, width, height, output, outpitch * 2, first, last);
+      snes_ntsc_blit(ntsc_svideo, input, pitch, burst_svideo, width, height, output, outpitch * 2, first, last);
    else
-      snes_ntsc_blit_hires(ntsc, input, pitch, burst, width, height, output, outpitch * 2, first, last);
+      snes_ntsc_blit_hires(ntsc_svideo, input, pitch, burst_svideo, width, height, output, outpitch * 2, first, last);
 
-   burst ^= burst_toggle;
+   burst_svideo ^= burst_toggle_svideo;
 }
 
 static void blargg_ntsc_snes_svideo_rgb565(unsigned width, unsigned height,
diff --git a/gfx/filters/snes_ntsc/snes_ntsc.c b/gfx/filters/snes_ntsc/snes_ntsc.c
index 6e383b61c3..7e1c60b7d4 100755
--- a/gfx/filters/snes_ntsc/snes_ntsc.c
+++ b/gfx/filters/snes_ntsc/snes_ntsc.c
@@ -1,4 +1,6 @@
 /* snes_ntsc 0.2.2. http://www.slack.net/~ant/ */
+#ifndef _BLARGG_SNES_NTSC_IMPLEMENTATION_H
+#define _BLARGG_SNES_NTSC_IMPLEMENTATION_H
 
 #include "snes_ntsc.h"
 
@@ -236,3 +238,5 @@ void snes_ntsc_blit_hires( snes_ntsc_t const* ntsc, SNES_NTSC_IN_T const* input,
 }
 
 #endif
+
+#endif
diff --git a/gfx/filters/snes_ntsc/snes_ntsc_impl.h b/gfx/filters/snes_ntsc/snes_ntsc_impl.h
index 1d7adc78b8..2d3c654589 100755
--- a/gfx/filters/snes_ntsc/snes_ntsc_impl.h
+++ b/gfx/filters/snes_ntsc/snes_ntsc_impl.h
@@ -1,4 +1,6 @@
 /* snes_ntsc 0.2.2. http://www.slack.net/~ant/ */
+#ifndef __BLARGG_SNES_NTSC_IMPLEMENTATION_H
+#define __BLARGG_SNES_NTSC_IMPLEMENTATION_H
 
 /* Common implementation of NTSC filters */
 
@@ -437,3 +439,5 @@ static void correct_errors( snes_ntsc_rgb_t color, snes_ntsc_rgb_t* out );
 	#endif
 
 #endif
+
+#endif