diff --git a/src/decaf.c b/src/decaf.c
index e586c48..28c224e 100644
--- a/src/decaf.c
+++ b/src/decaf.c
@@ -318,9 +318,7 @@ snv decaf_448_subx(
 snv decaf_448_montmul (
     decaf_448_scalar_t out,
     const decaf_448_scalar_t a,
-    const decaf_448_scalar_t b,
-    const decaf_448_scalar_t p,
-    decaf_word_t montgomery_factor
+    const decaf_448_scalar_t b
 ) {
     unsigned int i,j;
     decaf_word_t accum[DECAF_448_SCALAR_LIMBS+1] = {0};
@@ -338,9 +336,9 @@ snv decaf_448_montmul (
         }
         accum[j] = chain;
         
-        mand = accum[0] * montgomery_factor;
+        mand = accum[0] * DECAF_MONTGOMERY_FACTOR;
         chain = 0;
-        mier = p->limb;
+        mier = decaf_448_scalar_p->limb;
         for (j=0; j<DECAF_448_SCALAR_LIMBS; j++) {
             chain += (decaf_dword_t)mand*mier[j] + accum[j];
             if (j) accum[j-1] = chain;
@@ -352,7 +350,7 @@ snv decaf_448_montmul (
         hi_carry = chain >> WBITS;
     }
     
-    decaf_448_subx(out, accum, p, p, hi_carry);
+    decaf_448_subx(out, accum, decaf_448_scalar_p, decaf_448_scalar_p, hi_carry);
 }
 
 void decaf_448_scalar_mul (
@@ -360,8 +358,8 @@ void decaf_448_scalar_mul (
     const decaf_448_scalar_t a,
     const decaf_448_scalar_t b
 ) {
-    decaf_448_montmul(out,a,b,decaf_448_scalar_p,DECAF_MONTGOMERY_FACTOR);
-    decaf_448_montmul(out,out,decaf_448_scalar_r2,decaf_448_scalar_p,DECAF_MONTGOMERY_FACTOR);
+    decaf_448_montmul(out,a,b);
+    decaf_448_montmul(out,out,decaf_448_scalar_r2);
 }
 
 decaf_bool_t decaf_448_scalar_invert (
@@ -370,10 +368,10 @@ decaf_bool_t decaf_448_scalar_invert (
 ) {
     decaf_448_scalar_t b, ma;
     int i;
-    decaf_448_montmul(b,decaf_448_scalar_one,decaf_448_scalar_r2,decaf_448_scalar_p,DECAF_MONTGOMERY_FACTOR);
-    decaf_448_montmul(ma,a,decaf_448_scalar_r2,decaf_448_scalar_p,DECAF_MONTGOMERY_FACTOR);
+    decaf_448_montmul(b,decaf_448_scalar_one,decaf_448_scalar_r2);
+    decaf_448_montmul(ma,a,decaf_448_scalar_r2);
     for (i=DECAF_448_SCALAR_BITS-1; i>=0; i--) {
-        decaf_448_montmul(b,b,b,decaf_448_scalar_p,DECAF_MONTGOMERY_FACTOR);
+        decaf_448_montmul(b,b,b);
             
         decaf_word_t w = decaf_448_scalar_p->limb[i/WBITS];
         if (i<WBITS) {
@@ -381,11 +379,11 @@ decaf_bool_t decaf_448_scalar_invert (
             w-=2;
         }
         if (1 & w>>(i%WBITS)) {
-            decaf_448_montmul(b,b,ma,decaf_448_scalar_p,DECAF_MONTGOMERY_FACTOR);
+            decaf_448_montmul(b,b,ma);
         }
     }
 
-    decaf_448_montmul(out,b,decaf_448_scalar_one,decaf_448_scalar_p,DECAF_MONTGOMERY_FACTOR);
+    decaf_448_montmul(out,b,decaf_448_scalar_one);
     decaf_448_scalar_destroy(b);
     decaf_448_scalar_destroy(ma);
     return ~decaf_448_scalar_eq(out,decaf_448_scalar_zero);
@@ -651,7 +649,7 @@ void decaf_448_scalar_decode_long(
     
     while (i) {
         i -= DECAF_448_SER_BYTES;
-        decaf_448_montmul(t1,t1,decaf_448_scalar_r2,decaf_448_scalar_p,DECAF_MONTGOMERY_FACTOR);
+        decaf_448_montmul(t1,t1,decaf_448_scalar_r2);
         ignore_result( decaf_448_scalar_decode(t2, ser+i) );
         decaf_448_scalar_add(t1, t1, t2);
     }
diff --git a/src/decaf_fast.c b/src/decaf_fast.c
index 62857b2..f48300e 100644
--- a/src/decaf_fast.c
+++ b/src/decaf_fast.c
@@ -294,9 +294,7 @@ snv decaf_448_subx(
 snv decaf_448_montmul (
     decaf_448_scalar_t out,
     const decaf_448_scalar_t a,
-    const decaf_448_scalar_t b,
-    const decaf_448_scalar_t p,
-    decaf_word_t montgomery_factor
+    const decaf_448_scalar_t b
 ) {
     unsigned int i,j;
     decaf_word_t accum[DECAF_448_SCALAR_LIMBS+1] = {0};
@@ -314,9 +312,9 @@ snv decaf_448_montmul (
         }
         accum[j] = chain;
         
-        mand = accum[0] * montgomery_factor;
+        mand = accum[0] * DECAF_MONTGOMERY_FACTOR;
         chain = 0;
-        mier = p->limb;
+        mier = decaf_448_scalar_p->limb;
         for (j=0; j<DECAF_448_SCALAR_LIMBS; j++) {
             chain += (decaf_dword_t)mand*mier[j] + accum[j];
             if (j) accum[j-1] = chain;
@@ -328,7 +326,7 @@ snv decaf_448_montmul (
         hi_carry = chain >> WBITS;
     }
     
-    decaf_448_subx(out, accum, p, p, hi_carry);
+    decaf_448_subx(out, accum, decaf_448_scalar_p, decaf_448_scalar_p, hi_carry);
 }
 
 void decaf_448_scalar_mul (
@@ -336,8 +334,8 @@ void decaf_448_scalar_mul (
     const decaf_448_scalar_t a,
     const decaf_448_scalar_t b
 ) {
-    decaf_448_montmul(out,a,b,decaf_448_scalar_p,DECAF_MONTGOMERY_FACTOR);
-    decaf_448_montmul(out,out,decaf_448_scalar_r2,decaf_448_scalar_p,DECAF_MONTGOMERY_FACTOR);
+    decaf_448_montmul(out,a,b);
+    decaf_448_montmul(out,out,decaf_448_scalar_r2);
 }
 
 /* PERF: could implement this */
@@ -345,7 +343,7 @@ siv decaf_448_montsqr (
     decaf_448_scalar_t out,
     const decaf_448_scalar_t a
 ) {
-    decaf_448_montmul(out,a,a,decaf_448_scalar_p,DECAF_MONTGOMERY_FACTOR);
+    decaf_448_montmul(out,a,a);
 }
 
 decaf_bool_t decaf_448_scalar_invert (
@@ -353,17 +351,17 @@ decaf_bool_t decaf_448_scalar_invert (
     const decaf_448_scalar_t a
 ) {
     decaf_448_scalar_t chain[7], tmp;
-    decaf_448_montmul(chain[0],a,decaf_448_scalar_r2,decaf_448_scalar_p,DECAF_MONTGOMERY_FACTOR);
+    decaf_448_montmul(chain[0],a,decaf_448_scalar_r2);
     
     unsigned int i,j;
     /* Addition chain generated by a not-too-clever SAGE script.  First part: compute a^(2^222-1) */
-    struct { uint8_t widx, sidx, sct, midx; } muls [] = {
+    const struct { uint8_t widx, sidx, sct, midx; } muls [] = {
         {2,0,1,0}, {3,2,1,0}, {4,3,1,0}, {5,4,1,0}, /* 0x3,7,f,1f */
         {1,5,1,0}, {1,1,3,3}, {6,1,9,1}, {1,6,1,0}, {6,1,18,6}, /* a^(2^37-1) */
         {1,6,37,6}, {1,1,37,6}, {1,1,111,1} /* a^(2^222-1) */
     };
     /* Second part: sliding window */
-    struct { uint8_t sct, midx; } muls1 [] = {
+    const struct { uint8_t sct, midx; } muls1 [] = {
         {6, 5}, {4, 2}, {3, 0}, {2, 0}, {4, 0}, {8, 5},
         {2, 0}, {5, 3}, {4, 0}, {4, 0}, {5, 3}, {3, 2},
         {3, 2}, {3, 2}, {2, 0}, {3, 0}, {4, 2}, {2, 0},
@@ -382,7 +380,7 @@ decaf_bool_t decaf_448_scalar_invert (
         for (j=1; j<muls[i].sct; j++) {
             decaf_448_montsqr(tmp, tmp);
         }
-        decaf_448_montmul(chain[muls[i].widx], tmp, chain[muls[i].midx], decaf_448_scalar_p,DECAF_MONTGOMERY_FACTOR);
+        decaf_448_montmul(chain[muls[i].widx], tmp, chain[muls[i].midx]);
     }
     
     for (i=0; i<sizeof(muls1)/sizeof(muls1[0]); i++) {
@@ -390,10 +388,10 @@ decaf_bool_t decaf_448_scalar_invert (
         for (j=1; j<muls1[i].sct; j++) {
             decaf_448_montsqr(tmp, tmp);
         }
-        decaf_448_montmul(chain[1], tmp, chain[muls1[i].midx], decaf_448_scalar_p,DECAF_MONTGOMERY_FACTOR);
+        decaf_448_montmul(chain[1], tmp, chain[muls1[i].midx]);
     }
     
-    decaf_448_montmul(out,chain[1],decaf_448_scalar_one,decaf_448_scalar_p,DECAF_MONTGOMERY_FACTOR);
+    decaf_448_montmul(out,chain[1],decaf_448_scalar_one);
     for (i=0; i<sizeof(chain)/sizeof(chain[0]); i++) {
         decaf_448_scalar_destroy(chain[i]);
     }
@@ -701,7 +699,7 @@ decaf_bool_t decaf_448_scalar_decode(
         accum = (accum + s->limb[i] - decaf_448_scalar_p->limb[i]) >> WBITS;
     }
     
-    decaf_448_montmul(s,s,decaf_448_scalar_r1,decaf_448_scalar_p,DECAF_MONTGOMERY_FACTOR); /* ham-handed reduce */
+    decaf_448_montmul(s,s,decaf_448_scalar_r1); /* ham-handed reduce */
     
     return accum;
 }
@@ -753,14 +751,14 @@ void decaf_448_scalar_decode_long(
     if (ser_len == sizeof(*ser)) {
         assert(i==0);
         /* ham-handed reduce */
-        decaf_448_montmul(s,t1,decaf_448_scalar_r1,decaf_448_scalar_p,DECAF_MONTGOMERY_FACTOR);
+        decaf_448_montmul(s,t1,decaf_448_scalar_r1);
         decaf_448_scalar_destroy(t1);
         return;
     }
 
     while (i) {
         i -= DECAF_448_SER_BYTES;
-        decaf_448_montmul(t1,t1,decaf_448_scalar_r2,decaf_448_scalar_p,DECAF_MONTGOMERY_FACTOR);
+        decaf_448_montmul(t1,t1,decaf_448_scalar_r2);
         ignore_result( decaf_448_scalar_decode(t2, ser+i) );
         decaf_448_scalar_add(t1, t1, t2);
     }