diff --git a/include/osmocom/core/utils.h b/include/osmocom/core/utils.h
index 976d4a8..0b54c88 100644
--- a/include/osmocom/core/utils.h
+++ b/include/osmocom/core/utils.h
@@ -7,6 +7,7 @@
 #include <osmocom/core/backtrace.h>
 #include <osmocom/core/talloc.h>
 #include <osmocom/core/panic.h>
+#include <osmocom/core/defs.h>
 
 /*! \defgroup utils General-purpose utility functions
  *  @{
@@ -57,8 +58,18 @@
 
 #define osmo_static_assert(exp, name) typedef int dummy##name [(exp) ? 1 : -1] __attribute__((__unused__));
 
-void osmo_str2lower(char *out, const char *in);
-void osmo_str2upper(char *out, const char *in);
+void osmo_str2lower(char *out, const char *in)
+	OSMO_DEPRECATED("Use osmo_str_tolower() or osmo_str_tolower_buf() instead,"
+			" to properly check target memory bounds");
+void osmo_str2upper(char *out, const char *in)
+	OSMO_DEPRECATED("Use osmo_str_toupper() or osmo_str_toupper_buf() instead,"
+			" to properly check target memory bounds");
+
+size_t osmo_str_tolower_buf(char *dest, size_t dest_len, const char *src);
+const char *osmo_str_tolower(const char *src);
+
+size_t osmo_str_toupper_buf(char *dest, size_t dest_len, const char *src);
+const char *osmo_str_toupper(const char *src);
 
 #define OSMO_SNPRINTF_RET(ret, rem, offset, len)		\
 do {								\