diff --git a/lib/nvmf/subsystem.c b/lib/nvmf/subsystem.c
index 6e36d3eba..096a63593 100644
--- a/lib/nvmf/subsystem.c
+++ b/lib/nvmf/subsystem.c
@@ -61,6 +61,22 @@ enum spdk_nvmf_nqn_domain_states {
 	SPDK_NVMF_DOMAIN_ACCEPT_ANY = 2
 };
 
+/* Returns true if is a valid ASCII string as defined by the NVMe spec */
+static bool
+spdk_nvmf_valid_ascii_string(const void *buf, size_t size)
+{
+	const uint8_t *str = buf;
+	size_t i;
+
+	for (i = 0; i < size; i++) {
+		if (str[i] < 0x20 || str[i] > 0x7E) {
+			return false;
+		}
+	}
+
+	return true;
+}
+
 static bool
 spdk_nvmf_valid_nqn(const char *nqn)
 {
@@ -1073,6 +1089,12 @@ spdk_nvmf_subsystem_set_sn(struct spdk_nvmf_subsystem *subsystem, const char *sn
 		return -1;
 	}
 
+	if (!spdk_nvmf_valid_ascii_string(sn, len)) {
+		SPDK_DEBUGLOG(SPDK_LOG_NVMF, "Non-ASCII sn\n");
+		SPDK_TRACEDUMP(SPDK_LOG_NVMF, "sn", sn, len);
+		return -1;
+	}
+
 	snprintf(subsystem->sn, sizeof(subsystem->sn), "%s", sn);
 
 	return 0;
diff --git a/test/unit/lib/nvmf/subsystem.c/subsystem_ut.c b/test/unit/lib/nvmf/subsystem.c/subsystem_ut.c
index 98e13f974..6ef252219 100644
--- a/test/unit/lib/nvmf/subsystem.c/subsystem_ut.c
+++ b/test/unit/lib/nvmf/subsystem.c/subsystem_ut.c
@@ -385,6 +385,26 @@ nvmf_test_create_subsystem(void)
 	free(tgt.subsystems);
 }
 
+static void
+test_spdk_nvmf_subsystem_set_sn(void)
+{
+	struct spdk_nvmf_subsystem subsystem = {};
+
+	/* Basic valid serial number */
+	CU_ASSERT(spdk_nvmf_subsystem_set_sn(&subsystem, "abcd xyz") == 0);
+	CU_ASSERT(strcmp(subsystem.sn, "abcd xyz") == 0);
+
+	/* Exactly 20 characters (valid) */
+	CU_ASSERT(spdk_nvmf_subsystem_set_sn(&subsystem, "12345678901234567890") == 0);
+	CU_ASSERT(strcmp(subsystem.sn, "12345678901234567890") == 0);
+
+	/* 21 characters (too long, invalid) */
+	CU_ASSERT(spdk_nvmf_subsystem_set_sn(&subsystem, "123456789012345678901") < 0);
+
+	/* Non-ASCII characters (invalid) */
+	CU_ASSERT(spdk_nvmf_subsystem_set_sn(&subsystem, "abcd\txyz") < 0);
+}
+
 int main(int argc, char **argv)
 {
 	CU_pSuite	suite = NULL;
@@ -402,7 +422,8 @@ int main(int argc, char **argv)
 
 	if (
 		CU_add_test(suite, "create_subsystem", nvmf_test_create_subsystem) == NULL ||
-		CU_add_test(suite, "nvmf_subsystem_add_ns", test_spdk_nvmf_subsystem_add_ns) == NULL) {
+		CU_add_test(suite, "nvmf_subsystem_add_ns", test_spdk_nvmf_subsystem_add_ns) == NULL ||
+		CU_add_test(suite, "nvmf_subsystem_set_sn", test_spdk_nvmf_subsystem_set_sn) == NULL) {
 		CU_cleanup_registry();
 		return CU_get_error();
 	}