diff --git a/src/storage_program.rs b/src/storage_program.rs
index bc540c1a8d..8cfef37bf0 100644
--- a/src/storage_program.rs
+++ b/src/storage_program.rs
@@ -15,6 +15,7 @@ pub enum StorageProgram {
 }
 
 pub enum StorageError {
+    InvalidArgument,
     InvalidUserData,
 }
 
@@ -40,6 +41,11 @@ pub fn process_instruction(
     pix: usize,
     _accounts: &mut [&mut Account],
 ) -> Result<(), StorageError> {
+    // accounts_keys[0] must be signed
+    if tx.signed_key(pix, 0).is_none() {
+        Err(StorageError::InvalidArgument)?;
+    }
+
     if let Ok(syscall) = deserialize(tx.userdata(pix)) {
         match syscall {
             StorageProgram::SubmitMiningProof { sha_state } => {
diff --git a/src/vote_program.rs b/src/vote_program.rs
index e7d66e2188..056896535c 100644
--- a/src/vote_program.rs
+++ b/src/vote_program.rs
@@ -70,12 +70,20 @@ pub fn process_instruction(
     instruction_index: usize,
     accounts: &mut [&mut Account],
 ) -> Result<()> {
+    // all vote instructions require that accounts_keys[0] be a signer
+    if tx.signed_key(instruction_index, 0).is_none() {
+        Err(Error::InvalidArguments)?;
+    }
+
     match deserialize(tx.userdata(instruction_index)) {
         Ok(VoteInstruction::RegisterAccount) => {
+            if !check_id(&accounts[1].owner) {
+                error!("accounts[1] is not assigned to the VOTE_PROGRAM");
+                Err(Error::InvalidArguments)?;
+            }
+
             // TODO: a single validator could register multiple "vote accounts"
             // which would clutter the "accounts" structure. See github issue 1654.
-            accounts[1].owner = id();
-
             let mut vote_state = VoteProgram {
                 votes: VecDeque::new(),
                 node_id: *tx.from(),