diff --git a/model/riscv_insts_aext.sail b/model/riscv_insts_aext.sail
index 2e0eb9c73..cd90b6a5f 100644
--- a/model/riscv_insts_aext.sail
+++ b/model/riscv_insts_aext.sail
@@ -67,20 +67,10 @@ function clause execute(LOADRES(aq, rl, rs1, width, rd)) = {
   match ext_data_get_addr(rs1, zeros(), Read(Data), width) {
     Ext_DataAddr_Error(e)  => { ext_handle_data_check_error(e); RETIRE_FAIL },
     Ext_DataAddr_OK(vaddr) => {
-      let aligned : bool =
-          /* BYTE and HALF would only occur due to invalid decodes, but it doesn't hurt
-          * to treat them as valid here; otherwise we'd need to throw an internal_error.
-          */
-          match width {
-            BYTE   => true,
-            HALF   => vaddr[0..0] == 0b0,
-            WORD   => vaddr[1..0] == 0b00,
-            DOUBLE => vaddr[2..0] == 0b000
-          };
       /* "LR faults like a normal load, even though it's in the AMO major opcode space."
         * - Andrew Waterman, isa-dev, 10 Jul 2018.
         */
-      if not(aligned)
+      if not(is_aligned(vaddr, width))
       then { handle_mem_exception(vaddr, E_Load_Addr_Align()); RETIRE_FAIL }
       else match translateAddr(vaddr, Read(Data)) {
               TR_Failure(e, _)    => { handle_mem_exception(vaddr, e); RETIRE_FAIL },
@@ -123,17 +113,7 @@ function clause execute (STORECON(aq, rl, rs2, rs1, width, rd)) = {
     match ext_data_get_addr(rs1, zeros(), Write(Data), width) {
       Ext_DataAddr_Error(e)  => { ext_handle_data_check_error(e); RETIRE_FAIL },
       Ext_DataAddr_OK(vaddr) => {
-        let aligned : bool =
-          /* BYTE and HALF would only occur due to invalid decodes, but it doesn't hurt
-            * to treat them as valid here; otherwise we'd need to throw an internal_error.
-            */
-          match width {
-            BYTE   => true,
-            HALF   => vaddr[0..0] == 0b0,
-            WORD   => vaddr[1..0] == 0b00,
-            DOUBLE => vaddr[2..0] == 0b000
-          };
-        if not(aligned)
+        if not(is_aligned(vaddr, width))
         then { handle_mem_exception(vaddr, E_SAMO_Addr_Align()); RETIRE_FAIL }
         else {
           if match_reservation(vaddr) == false then {
@@ -208,7 +188,9 @@ function clause execute (AMO(op, aq, rl, rs2, rs1, width, rd)) = {
   match ext_data_get_addr(rs1, zeros(), ReadWrite(Data, Data), width) {
     Ext_DataAddr_Error(e)  => { ext_handle_data_check_error(e); RETIRE_FAIL },
     Ext_DataAddr_OK(vaddr) => {
-      match translateAddr(vaddr, ReadWrite(Data, Data)) {
+      if not(is_aligned(vaddr, width))
+      then { handle_mem_exception(vaddr, E_SAMO_Addr_Align()); RETIRE_FAIL }
+      else match translateAddr(vaddr, ReadWrite(Data, Data)) {
         TR_Failure(e, _) => { handle_mem_exception(vaddr, e); RETIRE_FAIL },
         TR_Address(addr, _) => {
           let eares : MemoryOpResult(unit) = match (width, sizeof(xlen)) {
diff --git a/model/riscv_insts_base.sail b/model/riscv_insts_base.sail
index 25891c94f..2b2fd8f77 100644
--- a/model/riscv_insts_base.sail
+++ b/model/riscv_insts_base.sail
@@ -313,14 +313,17 @@ function process_load(rd, vaddr, value, is_unsigned) =
     MemException(e)  => { handle_mem_exception(vaddr, e); RETIRE_FAIL }
   }
 
+function is_aligned(vaddr : xlenbits, width : word_width) -> bool =
+  match width {
+    BYTE   => true,
+    HALF   => vaddr[0..0] == zeros(),
+    WORD   => vaddr[1..0] == zeros(),
+    DOUBLE => vaddr[2..0] == zeros(),
+  }
+
+// Return true if the address is misaligned and misaligned accesses are not supported.
 function check_misaligned(vaddr : xlenbits, width : word_width) -> bool =
-  if   plat_enable_misaligned_access() then false
-  else match width {
-         BYTE   => false,
-         HALF   => vaddr[0] == bitone,
-         WORD   => vaddr[0] == bitone | vaddr[1] == bitone,
-         DOUBLE => vaddr[0] == bitone | vaddr[1] == bitone | vaddr[2] == bitone
-       }
+  not(plat_enable_misaligned_access()) & not(is_aligned(vaddr, width))
 
 function clause execute(LOAD(imm, rs1, rd, is_unsigned, width, aq, rl)) = {
   let offset : xlenbits = sign_extend(imm);