diff --git a/tests/lib/subdir.am b/tests/lib/subdir.am
index 6c897b132e..62b194439f 100644
--- a/tests/lib/subdir.am
+++ b/tests/lib/subdir.am
@@ -148,7 +148,7 @@ check_PROGRAMS += tests/lib/test_checksum
 tests_lib_test_checksum_CFLAGS = $(TESTS_CFLAGS)
 tests_lib_test_checksum_CPPFLAGS = $(TESTS_CPPFLAGS)
 tests_lib_test_checksum_LDADD = $(ALL_TESTS_LDADD)
-tests_lib_test_checksum_SOURCES = tests/lib/test_checksum.c
+tests_lib_test_checksum_SOURCES = tests/lib/test_checksum.c tests/helpers/c/prng.c
 
 
 check_PROGRAMS += tests/lib/test_graph
diff --git a/tests/lib/test_checksum.c b/tests/lib/test_checksum.c
index 0eedb96a5e..9a7f2b1472 100644
--- a/tests/lib/test_checksum.c
+++ b/tests/lib/test_checksum.c
@@ -24,6 +24,7 @@
 
 #include "checksum.h"
 #include "network.h"
+#include "prng.h"
 
 struct thread_master *master;
 
@@ -468,24 +469,19 @@ int main(int argc, char **argv)
 	uint8_t buffer[BUFSIZE];
 	int exercise = 0;
 #define EXERCISESTEP 257
-	srandom(time(NULL));
+	struct prng *prng = prng_new(0);
 
 	while (1) {
 		uint16_t ospfd, isisd, lib, in_csum, in_csum_res, in_csum_rfc;
-		int i, j;
+		int i;
 
 		exercise += EXERCISESTEP;
 		exercise %= MAXDATALEN;
 
 		printf("\rexercising length %d\033[K", exercise);
 
-		for (i = 0; i < exercise; i += sizeof(long int)) {
-			long int rand = frr_weak_random();
-
-			for (j = sizeof(long int); j > 0; j--)
-				buffer[i + (sizeof(long int) - j)] =
-					(rand >> (j * 8)) & 0xff;
-		}
+		for (i = 0; i < exercise; i++)
+			buffer[i] = prng_rand(prng);
 
 		in_csum = in_cksum(buffer, exercise);
 		in_csum_res = in_cksum_optimized(buffer, exercise);
@@ -537,6 +533,9 @@ int main(int argc, char **argv)
 				       iov[2].iov_len, in_csum_iov, in_csum);
 		}
 
+		if (exercise >= FLETCHER_CHECKSUM_VALIDATE)
+			continue;
+
 		ospfd = ospfd_checksum(buffer, exercise + sizeof(uint16_t),
 				       exercise);
 		if (verify(buffer, exercise + sizeof(uint16_t)))