diff --git a/meson.build b/meson.build
index b8131db9556d73ee8868ff17d0d4c71c8a84ea87..4fca2f2ad4e7fd5cf0f0fef0b92ff7729c99fe31 100644
--- a/meson.build
+++ b/meson.build
@@ -26,11 +26,11 @@ project(
   version : '0.0.1',
   license : 'MIT',
   meson_version : '>= 0.47',
-  default_options : ['c_std=c99', 'warning_level=2']
+  default_options : ['c_std=gnu99', 'warning_level=2']
 )
 
-if get_option('c_std') != 'c99'
-  error('c_std must be c99')
+if get_option('c_std') != 'gnu99'
+  error('c_std must be gnu99')
 endif
 
 sources = files(
diff --git a/texturator.c b/texturator.c
index 2675244a05e29f0a1bbaf842ca9c26c7910768a6..8695a63a129552215328e8f1ff1413bb810e3b87 100644
--- a/texturator.c
+++ b/texturator.c
@@ -95,7 +95,9 @@ static int error_frames;
 static int zoom = 1;
 static bool full;
 static bool stop;
+#ifdef HAVE_LIBPNG
 static bool png;
+#endif
 static GLenum target;
 static struct size {
 	unsigned x, y, z;
@@ -600,7 +602,7 @@ static void extract_pix(uint8_t *rgba, int *slice, int *level, bool *complemente
 {
 	*slice = (((float)rgba[0]) / 255.0) * 8.0;
 	*level = (((float)rgba[1]) / 255.0) * 16.0;
-	*complemented = (((float)rgba[2]) / 255.0) / 0.25;
+	*complemented = (((float)rgba[2]) / 255.0) / 0.25 != 0.0f;
 }
 
 static bool probe_pix(int x, int y, int w, int h, int s, int m)