diff --git a/src/Cryptol/PrimeEC.hs b/src/Cryptol/PrimeEC.hs
index e86771ba3..f230a1db8 100644
--- a/src/Cryptol/PrimeEC.hs
+++ b/src/Cryptol/PrimeEC.hs
@@ -202,13 +202,13 @@ ec_add p s t
 ec_sub :: PrimeModulus -> ProjectivePoint -> ProjectivePoint -> ProjectivePoint
 ec_sub p s t = ec_add p s u
   where u = case BN.bigNatSub (primeMod p) (py t) of
-              (# | y' #)    -> t{ py = y' }
+              (# | y' #)    -> t{ py = y' `BN.bigNatRem` (primeMod p) }
               (# (# #) | #) -> panic "ec_sub" ["cooridnate not in reduced form!", show (BN.bigNatToInteger (py t))]
 {-# INLINE ec_sub #-}
 
 
 ec_negate :: PrimeModulus -> ProjectivePoint -> ProjectivePoint
-ec_negate p s = s{ py = BN.bigNatSubUnsafe (primeMod p) (py s) }
+ec_negate p s = s{ py = (BN.bigNatSubUnsafe (primeMod p) (py s))  `BN.bigNatRem` (primeMod p) }
 {-# INLINE ec_negate #-}
 
 -- | Compute the elliptic curve group addition operation
@@ -294,7 +294,7 @@ ec_mult p d s
   | BN.bigNatIsZero (pz s) = zro
   | otherwise =
       case m of
-        0# -> panic "ec_mult" ["modulus too large", show (BN.bigNatToInteger (primeMod p))]
+        0# -> panic "ec_mult" ["integer with 0 width", show h]
         _  -> go m zro
 
  where
diff --git a/tests/issues/issue1675/issue1675.icry b/tests/issues/issue1675/issue1675.icry
new file mode 100644
index 000000000..716382ca5
--- /dev/null
+++ b/tests/issues/issue1675/issue1675.icry
@@ -0,0 +1,4 @@
+:m PrimeEC
+ec_mult`{13} 3 {x = 0, y = 0, z = 1}
+:t ec_mult`{13}
+ec_mult`{13} 3 {x = 0, y = 0, z = 1} : ProjectivePoint 13
\ No newline at end of file
diff --git a/tests/issues/issue1675/issue1675.icry.stdout b/tests/issues/issue1675/issue1675.icry.stdout
new file mode 100644
index 000000000..753daaa13
--- /dev/null
+++ b/tests/issues/issue1675/issue1675.icry.stdout
@@ -0,0 +1,6 @@
+Loading module Cryptol
+Loading module Cryptol
+Loading module PrimeEC
+{x = 0, y = 0, z = 1}
+ec_mult`{13} : Z 13 -> ProjectivePoint 13 -> ProjectivePoint 13
+{x = 0, y = 0, z = 1}