diff --git a/src/nmea/GxGGA.cpp b/src/nmea/GxGGA.cpp
index ad6cf41..c4f73a0 100644
--- a/src/nmea/GxGGA.cpp
+++ b/src/nmea/GxGGA.cpp
@@ -17,6 +17,10 @@
 #  include <stdlib_noniso.h>
 #endif
 
+#ifdef ARDUINO_ARCH_RENESAS
+extern "C" char * _EXFUN(strsep,(char **, const char *));
+#endif
+
 #include "util/gga.h"
 #include "util/common.h"
 #include "util/checksum.h"
diff --git a/src/nmea/GxRMC.cpp b/src/nmea/GxRMC.cpp
index 7a06b73..047ea1e 100644
--- a/src/nmea/GxRMC.cpp
+++ b/src/nmea/GxRMC.cpp
@@ -17,6 +17,10 @@
 #  include <stdlib_noniso.h>
 #endif
 
+#ifdef ARDUINO_ARCH_RENESAS
+extern "C" char * _EXFUN(strsep,(char **, const char *));
+#endif
+
 #include "util/rmc.h"
 #include "util/common.h"
 #include "util/checksum.h"