diff --git a/.gitignore b/.gitignore
index f77ab37..03519f3 100644
--- a/.gitignore
+++ b/.gitignore
@@ -11,6 +11,7 @@ test/test_xmss_core_XMSS*
 test/test_xmss_core_fast_XMSS*
 test/test_xmssmt_core_XMSSMT*
 test/test_xmssmt_core_fast_XMSSMT*
+test/test_determinism
 test/speed
 test/gen_testvectors
 test/xmss_keypair
diff --git a/Makefile b/Makefile
index 45e8d62..993e53c 100644
--- a/Makefile
+++ b/Makefile
@@ -15,6 +15,7 @@ TESTS = test/test_wots \
 		test/test_xmssmt_core_fast \
 		test/test_xmssmt_core \
 		test/test_xmssmt \
+		test/test_determinism \
 
 UI = test/xmss_keypair \
 	 test/xmss_sign \
diff --git a/test/test_determinism.c b/test/test_determinism.c
new file mode 100644
index 0000000..a54d5c5
--- /dev/null
+++ b/test/test_determinism.c
@@ -0,0 +1,57 @@
+#include <stdio.h>
+#include <stdint.h>
+#include <string.h>
+
+#include "../params.h"
+#include "../xmss.h"
+#include "../randombytes.h"
+
+#define MLEN 32
+
+int main()
+{
+    xmss_params params;
+    char *oidstr = "XMSS-SHA2_10_256";
+    uint32_t oid = 0x01000001;
+    unsigned int i;
+
+    fprintf(stderr, "Testing if XMSS-SHA2_10_256 signing is deterministic.. ");
+
+    xmss_str_to_oid(&oid, oidstr);
+    xmss_parse_oid(&params, oid);
+
+    unsigned char pk[XMSS_OID_LEN + params.publickey_bytes];
+    unsigned char sk[XMSS_OID_LEN + params.privatekey_bytes];
+    unsigned char sk2[XMSS_OID_LEN + params.privatekey_bytes];
+
+    unsigned char m[MLEN];
+    unsigned char sm[params.bytes + MLEN];
+    unsigned char sm2[params.bytes + MLEN];
+    unsigned long long smlen;
+
+    xmss_keypair(pk, sk, oid);
+
+    /* Duplicate the key, because the original will be modified. */
+    memcpy(sk2, sk, XMSS_OID_LEN + params.privatekey_bytes);
+
+    /* Sign a random message (but twice the same one). */
+    randombytes(m, MLEN);
+
+    xmss_sign(sk, sm, &smlen, m, MLEN);
+    xmss_sign(sk2, sm2, &smlen, m, MLEN);
+
+    /* Compare signature, and, if applicable, print the differences. */
+    if (memcmp(sm, sm2, params.bytes + MLEN)) {
+        fprintf(stderr, "signatures differ!\n");
+        for (i = 0; i < params.bytes + MLEN; i++) {
+            fprintf(stderr, (sm[i] != sm2[i] ? "x" : "."));
+        }
+        fprintf(stderr, "\n");
+        return -1;
+    }
+    else {
+        fprintf(stderr, "signatures are identical.\n");
+    }
+
+    return 0;
+}