diff --git a/main/opcodes/calldata-returndata-code.zkasm b/main/opcodes/calldata-returndata-code.zkasm
index e03cc4b4..d32f4622 100644
--- a/main/opcodes/calldata-returndata-code.zkasm
+++ b/main/opcodes/calldata-returndata-code.zkasm
@@ -385,12 +385,12 @@ opEXTCODECOPY:
     $ => D          :MLOAD(SP+1); [offset => D]
     $ => E          :MLOAD(SP); [size => E]
 
-    ; store lastMemOffset for memory expansion gas cost
-    C               :MSTORE(lastMemOffset)
+    ; store lastMemOffset for memory expansion gas cost, we store also at B to recover later
+    C => B           :MSTORE(lastMemOffset)
 
-    ; store lastMemLength for memory expansion gas cost
+    ; store lastMemLength for memory expansion gas cost, we store also at RCX to recover later
     ; compute memory expansion gas cost
-    E               :MSTORE(lastMemLength), CALL(saveMem); in: [lastMemOffset, lastMemLength]
+    E => RCX         :MSTORE(lastMemLength), CALL(saveMem); in: [lastMemOffset, lastMemLength]
 
     ; check out-of-gas
     ;${3*((E+31)/32)}
@@ -401,6 +401,8 @@ opEXTCODECOPY:
     ; 3*((E+31)/32)
     ; check out-of-gas
     GAS - 3 * E => GAS  :JMPN(outOfGas)
+    RCX => E
+    B => C
     ; if offset is above data len, length => offset
     D => A
     $ => B          :MLOAD(tmpContractLength)
@@ -504,8 +506,8 @@ opRETURNDATACOPY:
     $ => C          :MLOAD(SP); [size => C]
     ; store lastMemOffset for memory expansion gas cost
     D               :MSTORE(lastMemOffset)
-    ; store lastMemLength for memory expansion gas cost
-    C               :MSTORE(lastMemLength), CALL(saveMem); in: [lastMemOffset, lastMemLength]
+    ; store lastMemLength for memory expansion gas cost, we store also at RCX to recover later
+    C => RCX        :MSTORE(lastMemLength), CALL(saveMem); in: [lastMemOffset, lastMemLength]
     ; if retDataCTX is 0, end opcode execution
     $ => B          :MLOAD(retDataCTX), JMPZ(opRETURNDATACOPYEmpty)
     ; Load ret data length from last ctx
@@ -527,6 +529,7 @@ opRETURNDATACOPY:
     ; C is secured to be less than 32 bits after calling saveMem
     ;(C+31)/32
     C + 31 => A     :CALL(offsetUtil); in: [A: offset] out: [E: offset/32, C: offset%32]
+    RCX => C
     ; 3*((C+31)/32)
     ; check out-of-gas
     GAS - 3 * E => GAS  :JMPN(outOfGas)
diff --git a/main/opcodes/crypto.zkasm b/main/opcodes/crypto.zkasm
index 86d7d2de..579c781b 100644
--- a/main/opcodes/crypto.zkasm
+++ b/main/opcodes/crypto.zkasm
@@ -17,8 +17,8 @@ opSHA3:
     ; check out-of-gas
     GAS - %KECCAK_GAS => GAS :JMPN(outOfGas)
     SP - 1 => SP
-    $ => E          :MLOAD(SP--); [offset => E]
-    $ => C          :MLOAD(SP) ; [size => C]
+    $ => E, D       :MLOAD(SP--); [offset => E]
+    $ => C, B       :MLOAD(SP) ; [size => C]
 
     ; store lastMemOffset for memory expansion gas cost
     E               :MSTORE(lastMemOffset)
@@ -34,6 +34,9 @@ opSHA3:
     ; E is less than 32 bits because C is less than 32 bits and E = C/32
     ; 6*((C+31)/32)
     GAS - 6 * E => GAS  :JMPN(outOfGas)  ; dynamic_gas = 6 * minimum_word_size + memory_expansion_cost
+    ; Recover offset and size at E and C
+    D => E
+    B => C
     ; check keccak counters
     C + 1           :MSTORE(arithA)
     136             :MSTORE(arithB), CALL(divARITH); in: [arithA, arithB] out: [arithRes1: arithA/arithB, arithRes2: arithA%arithB]
diff --git a/main/precompiled/identity.zkasm b/main/precompiled/identity.zkasm
index 420bd502..5349d136 100644
--- a/main/precompiled/identity.zkasm
+++ b/main/precompiled/identity.zkasm
@@ -17,9 +17,10 @@ IDENTITY:
     $               :LT, JMPC(moveBalances)
 
     GAS - %IDENTITY_GAS => GAS :JMPN(outOfGas)
-    $ => C          :MLOAD(txCalldataLen)
+    $ => C, D       :MLOAD(txCalldataLen)
     ;(C+31)/32 => A
     C + 31 => A     :CALL(offsetUtil); in: [A: offset] out: [E: offset/32, C: offset%32]
+    D => C
     GAS - %IDENTITY_WORD_GAS*E => GAS   :JMPN(outOfGas)
     0 => E, D       :MSTORE(retDataOffset)
     C               :MSTORE(retDataLength)
diff --git a/main/precompiled/pre-sha2-256.zkasm b/main/precompiled/pre-sha2-256.zkasm
index d5558f0f..41123956 100644
--- a/main/precompiled/pre-sha2-256.zkasm
+++ b/main/precompiled/pre-sha2-256.zkasm
@@ -25,11 +25,11 @@ funcSHA256:
     ; GAS - staticGas
     GAS - %SHA2_256_GAS => GAS :JMPN(outOfGas)
 
-    $ => C          :MLOAD(txCalldataLen)
+    $ => C, D          :MLOAD(txCalldataLen)
 
     ;words => A  === (C+31)/32 => A
     C + 31 => A     :CALL(offsetUtil); in: [A: offset] out: [E: offset/32, C: offset%32]
-
+    D => C
     ; GAS - dynamicGas
     GAS - %SHA2_256_WORD_GAS*E => GAS   :JMPN(outOfGas)
 
diff --git a/main/utils.zkasm b/main/utils.zkasm
index ad2c1cf1..922aa23c 100644
--- a/main/utils.zkasm
+++ b/main/utils.zkasm
@@ -736,10 +736,10 @@ SHRarithBit:
     E                       :MSTORE(tmpVarESHX)
 
 SHRarithinit:
+    A => E                  :MSTORE(arithA)
     0 => B
     ; if A == 0 --> no shift
     $                       :EQ,JMPC(SHRarithfinal)
-    A => E                  :MSTORE(arithA)
     ; B bits
     D => B
     255 => A