diff --git a/hardware/arduino/sam/cores/arduino/itoa.h b/hardware/arduino/sam/cores/arduino/itoa.h
index 59af109473c..f2e483343b3 100644
--- a/hardware/arduino/sam/cores/arduino/itoa.h
+++ b/hardware/arduino/sam/cores/arduino/itoa.h
@@ -31,7 +31,14 @@ extern void itoa( int n, char s[] ) ;
 
 extern char* itoa( int value, char *string, int radix ) ;
 extern char* ltoa( long value, char *string, int radix ) ;
+#if __GNUC__ > 4 || \
+    (__GNUC__ == 4 && (__GNUC_MINOR__ > 9 || \
+                       (__GNUC_MINOR__ == 9 && \
+                        __GNUC_PATCHLEVEL__ > 2)))
+extern char* utoa( unsigned value, char *string, int radix ) ;
+#else
 extern char* utoa( unsigned long value, char *string, int radix ) ;
+#endif
 extern char* ultoa( unsigned long value, char *string, int radix ) ;
 #endif /* 0 */