diff --git a/src/test/script_tests.cpp b/src/test/script_tests.cpp
index 7a9ab0c0aab..f4269619dad 100644
--- a/src/test/script_tests.cpp
+++ b/src/test/script_tests.cpp
@@ -30,6 +30,7 @@
 
 #include <boost/test/unit_test.hpp>
 
+#include <secp256k1.h>
 #include <univalue.h>
 
 // Uncomment if you want to output updated JSON tests.
@@ -144,25 +145,17 @@ void static NegateSignatureS(std::vector<unsigned char>& vchSig) {
     r = std::vector<unsigned char>(vchSig.begin() + 4, vchSig.begin() + 4 + vchSig[3]);
     s = std::vector<unsigned char>(vchSig.begin() + 6 + vchSig[3], vchSig.begin() + 6 + vchSig[3] + vchSig[5 + vchSig[3]]);
 
-    // Really ugly to implement mod-n negation here, but it would be feature creep to expose such functionality from libsecp256k1.
-    static const unsigned char order[33] = {
-        0x00,
-        0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
-        0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFE,
-        0xBA, 0xAE, 0xDC, 0xE6, 0xAF, 0x48, 0xA0, 0x3B,
-        0xBF, 0xD2, 0x5E, 0x8C, 0xD0, 0x36, 0x41, 0x41
-    };
     while (s.size() < 33) {
         s.insert(s.begin(), 0x00);
     }
-    int carry = 0;
-    for (int p = 32; p >= 1; p--) {
-        int n = (int)order[p] - s[p] - carry;
-        s[p] = (n + 256) & 0xFF;
-        carry = (n < 0);
-    }
-    assert(carry == 0);
-    if (s.size() > 1 && s[0] == 0 && s[1] < 0x80) {
+    assert(s[0] == 0);
+    // Perform mod-n negation of s by (ab)using libsecp256k1
+    // (note that this function is meant to be used for negating secret keys,
+    //  but it works for any non-zero scalar modulo the group order, i.e. also for s)
+    int ret = secp256k1_ec_seckey_negate(secp256k1_context_static, s.data() + 1);
+    assert(ret);
+
+    if (s[1] < 0x80) {
         s.erase(s.begin());
     }