diff --git a/azure-pipelines.yml b/azure-pipelines.yml
index 4a40c3f..9f33fa3 100644
--- a/azure-pipelines.yml
+++ b/azure-pipelines.yml
@@ -131,13 +131,13 @@ steps:
           libffi-dev:i386
 
       mkdir -p bin
-      
-      cat < EOF > bin/gcc
+
+      cat << EOF > bin/gcc
       #!/bin/bash
       exec $(which gcc) -m32 "\$@"
       EOF
 
-      cat < EOF > bin/g++
+      cat << EOF > bin/g++
       #!/bin/bash
       exec $(which g++) -m32 "\$@"
       EOF
diff --git a/constantine/arithmetic/finite_fields_inversion.nim b/constantine/arithmetic/finite_fields_inversion.nim
index 99440ce..0057075 100644
--- a/constantine/arithmetic/finite_fields_inversion.nim
+++ b/constantine/arithmetic/finite_fields_inversion.nim
@@ -161,7 +161,10 @@ func inv*(r: var Fp, a: Fp) =
   # neither for Secp256k1 nor BN curves
   # Performance is slower than GCD
   # To be revisited with faster squaring/multiplications
-  r.mres.steinsGCD(a.mres, Fp.C.getR2modP(), Fp.C.Mod, Fp.C.getPrimePlus1div2())
+  when false: # Fp.C.canUse_BN_AddchainInversion():
+    r.invmod_addchain_bn(a)
+  else:
+    r.mres.steinsGCD(a.mres, Fp.C.getR2modP(), Fp.C.Mod, Fp.C.getPrimePlus1div2())
 
 func inv*(a: var Fp) =
   ## Inversion modulo p
@@ -175,5 +178,5 @@ func inv*(a: var Fp) =
   # Performance is slower than GCD
   # To be revisited with faster squaring/multiplications
   var t: typeof(a) # TODO: zero-init needed?
-  t.mres.steinsGCD(a.mres, Fp.C.getR2modP(), Fp.C.Mod, Fp.C.getPrimePlus1div2())
+  t.inv(a)
   a = t
diff --git a/constantine/config/curves_parser.nim b/constantine/config/curves_parser.nim
index 98162e2..eba05cb 100644
--- a/constantine/config/curves_parser.nim
+++ b/constantine/config/curves_parser.nim
@@ -346,6 +346,14 @@ proc genMainConstants(defs: var seq[CurveParams]): NimNode =
           exported($curve & "_BN_can_use_addchain_inversion"),
           newLit true
         )
+        curveExtraStmts.add newConstStmt(
+          exported($curve & "_BN_param_u"),
+          newCall(
+            bindSym"fromHex",
+            nnkBracketExpr.newTree(bindSym"BigInt", curveDef.bn_u_bitwidth),
+            curveDef.bn_u
+          )
+        )
       else:
         curveExtraStmts.add newConstStmt(
           exported($curve & "_BN_can_use_addchain_inversion"),