diff --git a/openbsc/tests/gprs/gprs_test.c b/openbsc/tests/gprs/gprs_test.c
new file mode 100644
index 0000000..7b0e641
--- /dev/null
+++ b/openbsc/tests/gprs/gprs_test.c
@@ -0,0 +1,51 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <inttypes.h>
+
+#include <openbsc/gprs_llc.h>
+
+#define ASSERT_FALSE(x) if (x)  { printf("Should have returned false.\n"); abort(); }
+#define ASSERT_TRUE(x)  if (!x) { printf("Should have returned true.\n"); abort(); }
+
+/**
+ * GSM 04.64 8.4.2 Receipt of unacknowledged information
+ */
+static int nu_is_retransmission(uint16_t nu, uint16_t vur)
+{
+	int ret = gprs_llc_is_retransmit(nu, vur);
+	printf("N(U) = %d, V(UR) = %d => %s\n", nu, vur,
+	       ret == 1 ? "retransmit" : "new");
+	return ret;
+}
+
+static void test_8_4_2()
+{
+	printf("Testing gprs_llc_is_retransmit.\n");
+
+	ASSERT_FALSE(nu_is_retransmission(0, 0));
+	ASSERT_TRUE (nu_is_retransmission(0, 1));
+
+	/* expect 1... check for retransmissions */
+	ASSERT_TRUE (nu_is_retransmission(0, 1));
+	ASSERT_TRUE (nu_is_retransmission(511, 1));
+	ASSERT_TRUE (nu_is_retransmission(483, 1));
+	ASSERT_TRUE (nu_is_retransmission(482, 1));
+	ASSERT_FALSE(nu_is_retransmission(481, 1));
+
+	/* expect 511... check for retransmissions */
+	ASSERT_FALSE(nu_is_retransmission(0, 240)); // ahead
+	ASSERT_FALSE(nu_is_retransmission(0, 511)); // ahead
+	ASSERT_FALSE(nu_is_retransmission(1, 511)); // ahead
+	ASSERT_FALSE(nu_is_retransmission(511, 511)); // same
+	ASSERT_TRUE (nu_is_retransmission(510, 511)); // behind
+	ASSERT_TRUE (nu_is_retransmission(481, 511)); // behind
+	ASSERT_FALSE(nu_is_retransmission(479, 511)); // wrapped
+}
+
+int main(int argc, char **argv)
+{
+	test_8_4_2();
+
+	printf("Done.\n");
+	return EXIT_SUCCESS;
+}