diff --git a/src/neonucleus.h b/src/neonucleus.h
index 85c489f..d807836 100644
--- a/src/neonucleus.h
+++ b/src/neonucleus.h
@@ -165,8 +165,10 @@ size_t nn_unicode_codepointSize(unsigned int codepoint);
 const char *nn_unicode_codepointToChar(unsigned int codepoint, size_t *len);
 size_t nn_unicode_charWidth(unsigned int codepoint);
 size_t nn_unicode_wlen(const char *s);
-void nn_unicode_upper(char *s);
-void nn_unicode_lower(char *s);
+unsigned int nn_unicode_upperCodepoint(unsigned int codepoint);
+char *nn_unicode_upper(const char *s);
+unsigned int nn_unicode_lowerCodepoint(unsigned int codepoint);
+char *nn_unicode_lower(const char *s);
 
 double nn_realTime();
 double nn_realTimeClock(void *_);
diff --git a/src/unicode.c b/src/unicode.c
index f9ca12d..957eec2 100644
--- a/src/unicode.c
+++ b/src/unicode.c
@@ -168,10 +168,13 @@ const char *nn_unicode_codepointToChar(unsigned int codepoint, size_t *len) {
     return buffer;
 }
 
+// NOT IMPLEMENTED YET
+
 size_t nn_unicode_charWidth(unsigned int codepoint);
 
 size_t nn_unicode_wlen(const char *s);
 
-// NOT IMPLEMENTED YET
-void nn_unicode_upper(char *s);
-void nn_unicode_lower(char *s);
+unsigned int nn_unicode_upperCodepoint(unsigned int codepoint);
+char *nn_unicode_upper(const char *s);
+unsigned int nn_unicode_lowerCodepoint(unsigned int codepoint);
+char *nn_unicode_lower(const char *s);