diff --git a/crates/interpreter/src/exec.rs b/crates/interpreter/src/exec.rs
index eaac31b3..ddf41b50 100644
--- a/crates/interpreter/src/exec.rs
+++ b/crates/interpreter/src/exec.rs
@@ -762,19 +762,24 @@ impl<'m> Thread<'m> {
         use Instr::*;
         let inst_id = self.frame().inst_id;
         let inst = &mut store.insts[inst_id];
+        let side_table = self.frame().side_table;
+        let val_cnt =
+            if !side_table.is_empty() { Some(side_table[0].view().val_cnt) } else { None };
+        let pop_cnt =
+            if !side_table.is_empty() { Some(side_table[0].view().pop_cnt) } else { None };
         match self.parser.parse_instr().into_ok() {
             Unreachable => return Err(trap()),
             Nop => (),
-            Block(b) => self.push_label(self.blocktype(inst, &b), LabelKind::Block),
-            Loop(b) => self.push_label(self.blocktype(inst, &b), LabelKind::Loop),
+            Block(b) => self.push_label(self.blocktype(inst, &b), LabelKind::Block, val_cnt),
+            Loop(b) => self.push_label(self.blocktype(inst, &b), LabelKind::Loop, val_cnt),
             If(b) => match self.pop_value().unwrap_i32() {
                 0 => {
                     self.take_jump(0);
-                    self.push_label(self.blocktype(inst, &b), LabelKind::Block);
+                    self.push_label(self.blocktype(inst, &b), LabelKind::Block, val_cnt);
                 }
                 _ => {
                     self.frame().skip_jump();
-                    self.push_label(self.blocktype(inst, &b), LabelKind::If);
+                    self.push_label(self.blocktype(inst, &b), LabelKind::If, val_cnt);
                 }
             },
             Else => {
@@ -782,10 +787,10 @@ impl<'m> Thread<'m> {
                 return Ok(self.exit_label());
             }
             End => return Ok(self.exit_label()),
-            Br(l) => return Ok(self.pop_label(l, 0)),
+            Br(l) => return Ok(self.pop_label(l, 0, pop_cnt)),
             BrIf(l) => {
                 if self.pop_value().unwrap_i32() != 0 {
-                    return Ok(self.pop_label(l, 0));
+                    return Ok(self.pop_label(l, 0, pop_cnt));
                 }
                 self.frame().skip_jump();
             }
@@ -793,8 +798,11 @@ impl<'m> Thread<'m> {
                 // In validation for BrTable, the side table entry for the last label index is
                 // created at first.
                 let i = self.pop_value().unwrap_i32() as usize;
-                return Ok(self
-                    .pop_label(ls.get(i).cloned().unwrap_or(ln), ls.get(i).map_or(0, |_| i + 1)));
+                return Ok(self.pop_label(
+                    ls.get(i).cloned().unwrap_or(ln),
+                    ls.get(i).map_or(0, |_| i + 1),
+                    pop_cnt,
+                ));
             }
             Return => return Ok(self.exit_frame()),
             Call(x) => return self.invoke(store, store.func_ptr(inst_id, x)),
@@ -1036,24 +1044,47 @@ impl<'m> Thread<'m> {
         self.values().split_off(len)
     }
 
-    fn push_label(&mut self, type_: FuncType<'m>, kind: LabelKind) {
+    fn push_label(&mut self, type_: FuncType<'m>, kind: LabelKind, val_cnt: Option<u32>) {
         let arity = match kind {
             LabelKind::Block | LabelKind::If => type_.results.len(),
             LabelKind::Loop => type_.params.len(),
         };
-        let label = Label { arity, values_cnt: type_.params.len() };
+        match kind {
+            LabelKind::If => {
+                if val_cnt.is_some() {
+                    debug_assert_eq!(arity as u32, val_cnt.unwrap())
+                }
+            }
+            LabelKind::Loop => {
+                // There is no side table entry for a loop that is only executed once.
+                if val_cnt.is_some() && !type_.params.is_empty() {
+                    debug_assert_eq!(arity as u32, val_cnt.unwrap())
+                }
+            }
+            _ => {}
+        }
+        let label = Label { arity, values_cnt: type_.params.len(), kind };
         self.label().values_cnt -= label.values_cnt;
         self.labels().push(label);
     }
 
-    fn pop_label(mut self, l: LabelIdx, offset: usize) -> ThreadResult<'m> {
+    fn pop_label(mut self, l: LabelIdx, offset: usize, pop_cnt: Option<u32>) -> ThreadResult<'m> {
         let i = self.labels().len() - l as usize - 1;
         if i == 0 {
             return self.exit_frame();
         }
         let frame = self.frame();
         let values_cnt: usize = frame.labels[i ..].iter().map(|label| label.values_cnt).sum();
-        let Label { arity, .. } = frame.labels.drain(i ..).next().unwrap();
+
+        let Label { arity, kind, .. } = frame.labels.drain(i ..).next().unwrap();
+        match kind {
+            LabelKind::Block => {}
+            _ => {
+                if pop_cnt.is_some() {
+                    debug_assert_eq!(values_cnt as u32 - arity as u32, pop_cnt.unwrap());
+                }
+            }
+        }
         let values_len = self.values().len();
         self.values().drain(values_len - values_cnt .. values_len - arity);
         self.label().values_cnt += arity;
@@ -1419,7 +1450,7 @@ impl<'m> Frame<'m> {
         inst_id: usize, arity: usize, ret: &'m [u8], locals: Vec<Val>,
         side_table: &'m [SideTableEntry],
     ) -> Self {
-        let label = Label { arity, values_cnt: 0 };
+        let label = Label { arity, values_cnt: 0, kind: LabelKind::Block };
         Frame { inst_id, arity, ret, locals, labels: vec![label], side_table }
     }
 
@@ -1439,6 +1470,7 @@ impl<'m> Frame<'m> {
 struct Label {
     arity: usize,
     values_cnt: usize,
+    kind: LabelKind,
 }
 
 #[derive(Debug)]