diff --git a/Documentation/ptp/testptp.c b/Documentation/ptp/testptp.c
index 13bddd5427bd28aa892f2b1bcbec5c26fed48ed2..f1ac2dae999e008ca7175b2eee0c482f144b9f12 100644
--- a/Documentation/ptp/testptp.c
+++ b/Documentation/ptp/testptp.c
@@ -19,6 +19,7 @@
  */
 #include <errno.h>
 #include <fcntl.h>
+#include <inttypes.h>
 #include <math.h>
 #include <signal.h>
 #include <stdio.h>
@@ -496,14 +497,14 @@ int main(int argc, char *argv[])
 			interval = t2 - t1;
 			offset = (t2 + t1) / 2 - tp;
 
-			printf("system time: %ld.%ld\n",
+			printf("system time: %" PRId64 ".%u\n",
 				(pct+2*i)->sec, (pct+2*i)->nsec);
-			printf("phc    time: %ld.%ld\n",
+			printf("phc    time: %" PRId64 ".%u\n",
 				(pct+2*i+1)->sec, (pct+2*i+1)->nsec);
-			printf("system time: %ld.%ld\n",
+			printf("system time: %" PRId64 ".%u\n",
 				(pct+2*i+2)->sec, (pct+2*i+2)->nsec);
-			printf("system/phc clock time offset is %ld ns\n"
-				"system     clock time delay  is %ld ns\n",
+			printf("system/phc clock time offset is %" PRId64 " ns\n"
+			       "system     clock time delay  is %" PRId64 " ns\n",
 				offset, interval);
 		}