diff --git a/core/src/ggsw_ciphertext.rs b/core/src/ggsw_ciphertext.rs
index 67f4774..577bd6e 100644
--- a/core/src/ggsw_ciphertext.rs
+++ b/core/src/ggsw_ciphertext.rs
@@ -149,6 +149,8 @@ where
         };
 
         (0..self.rows()).for_each(|row_j| {
+            vec_znx_pt.data.zero();
+
             // Adds the scalar_znx_pt to the i-th limb of the vec_znx_pt
             module.vec_znx_add_scalar_inplace(&mut vec_znx_pt, 0, row_j, pt, 0);
             module.vec_znx_normalize_inplace(basek, &mut vec_znx_pt, 0, scrach_2);
@@ -177,8 +179,6 @@ where
                     module.vmp_prepare_row(self, row_j, col_i, &vec_znx_dft_ct);
                 }
             });
-
-            vec_znx_pt.data.zero(); // zeroes for next iteration
         });
     }
 
diff --git a/core/src/glwe_ciphertext.rs b/core/src/glwe_ciphertext.rs
index 245ee26..0fd6242 100644
--- a/core/src/glwe_ciphertext.rs
+++ b/core/src/glwe_ciphertext.rs
@@ -121,19 +121,33 @@ impl GLWECiphertext<Vec<u8>> {
         ksk_size: usize,
     ) -> usize {
         let res_dft: usize = module.bytes_of_vec_znx_dft(out_rank + 1, ksk_size);
-        let vmp: usize = module.vmp_apply_tmp_bytes(
-            out_size,
-            in_size,
-            in_size,
-            in_rank + 1,
-            out_rank + 1,
-            ksk_size,
-        ) + module.bytes_of_vec_znx_dft(in_rank, in_size);
+        let vmp: usize = module.vmp_apply_tmp_bytes(out_size, in_size, in_size, in_rank, out_rank + 1, ksk_size)
+            + module.bytes_of_vec_znx_dft(in_rank, in_size);
         let normalize: usize = module.vec_znx_big_normalize_tmp_bytes();
 
         return res_dft + (vmp | normalize);
     }
 
+    pub fn keyswitch_from_fourier_scratch_space(
+        module: &Module<FFT64>,
+        out_size: usize,
+        out_rank: usize,
+        in_size: usize,
+        in_rank: usize,
+        ksk_size: usize,
+    ) -> usize {
+        let res_dft = module.bytes_of_vec_znx_dft(out_rank + 1, ksk_size);
+
+        let vmp: usize = module.vmp_apply_tmp_bytes(out_size, in_size, in_size, in_rank, out_rank + 1, ksk_size)
+            + module.bytes_of_vec_znx_dft(in_rank, in_size);
+
+        let a0_big: usize = module.bytes_of_vec_znx_big(1, in_size) + module.vec_znx_idft_tmp_bytes();
+
+        let norm: usize = module.vec_znx_big_normalize_tmp_bytes();
+
+        res_dft + (vmp | a0_big | norm)
+    }
+
     pub fn keyswitch_inplace_scratch_space(module: &Module<FFT64>, out_size: usize, out_rank: usize, ksk_size: usize) -> usize {
         GLWECiphertext::keyswitch_scratch_space(module, out_size, out_rank, out_size, out_rank, ksk_size)
     }
@@ -322,7 +336,7 @@ where
             assert_eq!(lhs.n(), module.n());
             assert!(
                 scratch.available()
-                    >= GLWECiphertextFourier::keyswitch_scratch_space(
+                    >= GLWECiphertext::keyswitch_from_fourier_scratch_space(
                         module,
                         self.size(),
                         self.rank(),
diff --git a/core/src/glwe_ciphertext_fourier.rs b/core/src/glwe_ciphertext_fourier.rs
index 4c22507..135a2dd 100644
--- a/core/src/glwe_ciphertext_fourier.rs
+++ b/core/src/glwe_ciphertext_fourier.rs
@@ -91,22 +91,8 @@ impl GLWECiphertextFourier<Vec<u8>, FFT64> {
         in_rank: usize,
         ksk_size: usize,
     ) -> usize {
-        let res_dft: usize = module.bytes_of_vec_znx_dft(out_rank + 1, out_size);
-
-        let vmp = module.bytes_of_vec_znx_dft(in_rank, in_size)
-            + module.vmp_apply_tmp_bytes(
-                out_size,
-                in_size,
-                in_size,
-                in_rank + 1,
-                out_rank + 1,
-                ksk_size,
-            );
-        let res_small: usize = module.bytes_of_vec_znx(out_rank + 1, out_size);
-        let add_a0: usize = module.bytes_of_vec_znx_big(1, in_size) + module.vec_znx_idft_tmp_bytes();
-        let normalize: usize = module.vec_znx_big_normalize_tmp_bytes();
-
-        res_dft + (vmp | add_a0 | (res_small + normalize))
+        module.bytes_of_vec_znx(out_rank + 1, out_size)
+            + GLWECiphertext::keyswitch_from_fourier_scratch_space(module, out_size, out_rank, in_size, in_rank, ksk_size)
     }
 
     pub fn keyswitch_inplace_scratch_space(module: &Module<FFT64>, out_size: usize, out_rank: usize, ksk_size: usize) -> usize {
@@ -181,11 +167,11 @@ where
 
         let mut res_idft: GLWECiphertext<&mut [u8]> = GLWECiphertext::<&mut [u8]> {
             data: res_idft_data,
-            basek: self.basek,
-            k: self.k,
+            basek: lhs.basek,
+            k: lhs.k,
         };
 
-        res_idft.keyswitch_from_fourier(module, self, rhs, scratch1);
+        res_idft.keyswitch_from_fourier(module, lhs, rhs, scratch1);
 
         (0..cols_out).for_each(|i| {
             module.vec_znx_dft(self, i, &res_idft, i);