diff --git a/src/util/common.h b/src/util/common.h
index 25993cd26..ed10a86e2 100644
--- a/src/util/common.h
+++ b/src/util/common.h
@@ -6,9 +6,7 @@
 #ifndef COMMON_H
 #define COMMON_H
 
-#ifndef PSP2
 #include <ctype.h>
-#endif
 #include <fcntl.h>
 #include <inttypes.h>
 #include <limits.h>
diff --git a/src/util/png-io.c b/src/util/png-io.c
index cb9e90fdf..b16f068f1 100644
--- a/src/util/png-io.c
+++ b/src/util/png-io.c
@@ -84,8 +84,8 @@ bool PNGWritePixels(png_structp png, unsigned width, unsigned height, unsigned s
 bool PNGWriteCustomChunk(png_structp png, const char* name, size_t size, void* data) {
 	char realName[5];
 	strncpy(realName, name, 4);
-	realName[0] = tolower(realName[0]);
-	realName[1] = tolower(realName[1]);
+	realName[0] = tolower((int) realName[0]);
+	realName[1] = tolower((int) realName[1]);
 	realName[4] = '\0';
 	if (setjmp(png_jmpbuf(png))) {
 		return false;