diff --git a/tests/check_lib.c b/tests/check_lib.c
index 86155cc..7a30e3f 100644
--- a/tests/check_lib.c
+++ b/tests/check_lib.c
@@ -105,19 +105,16 @@ subcmd_prng (
     int   argc,
     char *argv[]
 ) {
-    static uint64_t seed[4];
-    int cnt = 0;
+    static uint64_t buf[4];
+    uint64_t *seed = NULL;
     int n = 0;
 
     getopt_foreach(argc, argv, ":s:n:") {
       case 's':
-        cnt = sscanf(optarg,
-                "%16" SCNx64 "%16" SCNx64 "%16" SCNx64 "%16" SCNx64,
-                &seed[0], &seed[1], &seed[2], &seed[3]);
-        if (cnt != 4) {
-            log_printf("bad seed '%s'", optarg);
+        if (0 != prng_seed_from_hex(buf, optarg)) {
             return -1;
         }
+        seed = buf;
         break;
 
       case 'n':
@@ -129,7 +126,7 @@ subcmd_prng (
         return -1;
     }
 
-    if (0 != prng_seed(cnt == 0 ? NULL : seed)) {
+    if (0 != prng_seed(seed)) {
         return -1;
     }
     for (; n > 0; --n) {
@@ -138,6 +135,21 @@ subcmd_prng (
     return 0;
 }
 
+int
+prng_seed_from_hex (
+    uint64_t   *buf,
+    char const *str
+) {
+    int cnt = sscanf(str,
+            "%16" SCNx64 "%16" SCNx64 "%16" SCNx64 "%16" SCNx64,
+            &buf[0], &buf[1], &buf[2], &buf[3]);
+    if (cnt != 4) {
+        log_printf("bad seed '%s'", optarg);
+        return -1;
+    }
+    return 0;
+}
+
 int
 main (
     int   argc,
diff --git a/tests/check_lib.h b/tests/check_lib.h
index eb6e0f7..2fa2b47 100644
--- a/tests/check_lib.h
+++ b/tests/check_lib.h
@@ -21,6 +21,8 @@
 #ifndef BOOKMARKFS_CHECK_LIB_H_
 #define BOOKMARKFS_CHECK_LIB_H_
 
+#include <stdint.h>
+
 #include "xstd.h"
 
 #define ASSERT_EXPR_INT(expr, r, cond, action_if_false)        \
@@ -45,4 +47,10 @@ check_watcher (
     char *argv[]
 );
 
+int
+prng_seed_from_hex (
+    uint64_t   *buf,
+    char const *str
+);
+
 #endif  /* !defined(BOOKMARKFS_CHECK_LIB_H_) */
diff --git a/tests/lib_prng.at b/tests/lib_prng.at
index 5155a56..5f1123f 100644
--- a/tests/lib_prng.at
+++ b/tests/lib_prng.at
@@ -18,16 +18,7 @@ ATX_CHECK_LIB([
         check-util-lib prng -s$1 -n$2
     }
 
-    gen_seed() {
-        seed_1=$(ath_fn_rand_u64_hex)
-        seed_2=$(ath_fn_rand_u64_hex)
-        seed_3=$(ath_fn_rand_u64_hex)
-        seed_4=$(ath_fn_rand_u64_hex)
-
-        echo $seed_1$seed_2$seed_3$seed_4
-    }
-
-    seed=$(gen_seed)
+    seed=$(ath_fn_prng_seed)
     count=32
 
     num_1=$(gen_num $seed $count)
diff --git a/tests/testsuite.at b/tests/testsuite.at
index c8bdb9f..60a95cd 100644
--- a/tests/testsuite.at
+++ b/tests/testsuite.at
@@ -93,6 +93,15 @@ AT_TEST_HELPER_FN([rand_base64], , , [
     echo $(head -c$1 /dev/urandom | base64 -w0)
 ])
 
+AT_TEST_HELPER_FN([prng_seed], , , [
+    seed_1=$(ath_fn_rand_u64_hex)
+    seed_2=$(ath_fn_rand_u64_hex)
+    seed_3=$(ath_fn_rand_u64_hex)
+    seed_4=$(ath_fn_rand_u64_hex)
+
+    echo $seed_1$seed_2$seed_3$seed_4
+])
+
 AT_BANNER([The Utility Library])
 m4_include([lib_hash.at])
 m4_include([lib_prng.at])