diff --git a/.checkpatch.conf b/.checkpatch.conf
index 71f34a2f..4f4ed543 100644
--- a/.checkpatch.conf
+++ b/.checkpatch.conf
@@ -53,6 +53,9 @@
 # Prefer stdint.h types over kernel types
 --ignore PREFER_KERNEL_TYPES
 
+# Don't ask to replace sscanf by kstrto
+--ignore SSCANF_TO_KSTRTO
+
 # Parentheses can make the code clearer
 --ignore UNNECESSARY_PARENTHESES
 
diff --git a/Makefile b/Makefile
index 49da9f93..125f1acf 100644
--- a/Makefile
+++ b/Makefile
@@ -26,7 +26,7 @@ PNGLDLIBS	:= `${PKG_CONFIG} --static --libs-only-l libpng`
 
 VERSION_STRING	:= `git describe --tags --dirty --always 2>/dev/null`
 
-WARNFLAGS	:= -Wall -Werror
+WARNFLAGS	:= -Werror -Wall -Wpedantic
 
 # Overridable CFLAGS
 CFLAGS		:= -g
diff --git a/src/asm/lexer.c b/src/asm/lexer.c
index 8696b140..b789f567 100644
--- a/src/asm/lexer.c
+++ b/src/asm/lexer.c
@@ -640,7 +640,6 @@ scanagain:
 
 	/* Check for line continuation character */
 	if (*pLexBuffer == '\\') {
-
 		/*
 		 * Look for line continuation character after a series of
 		 * spaces. This is also useful for files that use Windows line
diff --git a/src/asm/main.c b/src/asm/main.c
index 28659e53..4a551a88 100644
--- a/src/asm/main.c
+++ b/src/asm/main.c
@@ -147,10 +147,13 @@ void opt_Parse(char *s)
 	case 'z':
 		if (strlen(&s[1]) <= 2) {
 			int32_t result;
+			unsigned int fillchar;
 
-			result = sscanf(&s[1], "%x", &newopt.fillchar);
+			result = sscanf(&s[1], "%x", &fillchar);
 			if (!((result == EOF) || (result == 1)))
 				errx(1, "Invalid argument for option 'z'");
+
+			newopt.fillchar = fillchar;
 		} else {
 			errx(1, "Invalid argument for option 'z'");
 		}
diff --git a/src/gfx/makepng.c b/src/gfx/makepng.c
index 3f8fc24a..88654afb 100644
--- a/src/gfx/makepng.c
+++ b/src/gfx/makepng.c
@@ -317,9 +317,9 @@ static void rgba_png_palette(struct PNGImage *img,
 			     png_color **palette_ptr_ptr, int *num_colors)
 {
 	if (png_get_valid(img->png, img->info, PNG_INFO_PLTE))
-		return rgba_PLTE_palette(img, palette_ptr_ptr, num_colors);
+		rgba_PLTE_palette(img, palette_ptr_ptr, num_colors);
 	else
-		return rgba_build_palette(img, palette_ptr_ptr, num_colors);
+		rgba_build_palette(img, palette_ptr_ptr, num_colors);
 }
 
 static void rgba_PLTE_palette(struct PNGImage *img,