diff --git a/src/ops.rs b/src/ops.rs
index f6ef25004..e7162f65a 100644
--- a/src/ops.rs
+++ b/src/ops.rs
@@ -99,7 +99,7 @@ impl OpType {
     ///
     /// Returns None if there is no such port, or if the operation defines multiple non-dataflow ports.
     pub fn other_port_index(&self, dir: Direction) -> Option<Port> {
-        let non_df_count = self.validity_flags().non_df_port_count(dir).unwrap_or(1);
+        let non_df_count = self.non_df_port_count(dir).unwrap_or(1);
         if self.other_port(dir).is_some() && non_df_count == 1 {
             // if there is a static input it comes before the non_df_ports
             let static_input =
@@ -119,7 +119,6 @@ impl OpType {
         let signature = self.signature();
         let has_other_ports = self.other_port(dir).is_some();
         let non_df_count = self
-            .validity_flags()
             .non_df_port_count(dir)
             .unwrap_or(has_other_ports as usize);
         // if there is a static input it comes before the non_df_ports
@@ -214,6 +213,14 @@ pub trait OpTrait {
     fn other_output(&self) -> Option<EdgeKind> {
         None
     }
+
+    /// Get the number of non-dataflow multiports.
+    ///
+    /// If None, the operation must have exactly one non-dataflow port
+    /// if the operation type has other_edges, or zero otherwise.
+    fn non_df_port_count(&self, _dir: Direction) -> Option<usize> {
+        None
+    }
 }
 
 #[enum_dispatch]
diff --git a/src/ops/controlflow.rs b/src/ops/controlflow.rs
index 54adcf803..b6836ea70 100644
--- a/src/ops/controlflow.rs
+++ b/src/ops/controlflow.rs
@@ -3,8 +3,8 @@
 use smol_str::SmolStr;
 
 use crate::extension::ExtensionSet;
-use crate::type_row;
 use crate::types::{EdgeKind, FunctionType, Type, TypeRow};
+use crate::{type_row, Direction};
 
 use super::dataflow::DataflowOpTrait;
 use super::OpTag;
@@ -177,6 +177,15 @@ impl OpTrait for BasicBlock {
             BasicBlock::Exit { .. } => FunctionType::new(type_row![], type_row![]),
         }
     }
+
+    fn non_df_port_count(&self, dir: Direction) -> Option<usize> {
+        match self {
+            Self::DFB { tuple_sum_rows, .. } if dir == Direction::Outgoing => {
+                Some(tuple_sum_rows.len())
+            }
+            _ => None,
+        }
+    }
 }
 
 impl BasicBlock {
diff --git a/src/ops/validate.rs b/src/ops/validate.rs
index 6c6ff65cd..546d6cec6 100644
--- a/src/ops/validate.rs
+++ b/src/ops/validate.rs
@@ -11,7 +11,6 @@ use portgraph::{NodeIndex, PortOffset};
 use thiserror::Error;
 
 use crate::types::{Type, TypeRow};
-use crate::Direction;
 
 use super::{impl_validate_op, BasicBlock, OpTag, OpTrait, OpType, ValidateOp};
 
@@ -32,30 +31,12 @@ pub struct OpValidityFlags {
     pub requires_children: bool,
     /// Whether the children must form a DAG (no cycles).
     pub requires_dag: bool,
-    /// A strict requirement on the number of non-dataflow multiports.
-    ///
-    /// If not specified, the operation must have exactly one non-dataflow port
-    /// if the operation type has other_edges, or zero otherwise.
-    pub non_df_ports: (Option<usize>, Option<usize>),
     /// A validation check for edges between children
     ///
     // Enclosed in an `Option` to avoid iterating over the edges if not needed.
     pub edge_check: Option<fn(ChildrenEdgeData) -> Result<(), EdgeValidationError>>,
 }
 
-impl OpValidityFlags {
-    /// Get the number of non-dataflow multiports.
-    ///
-    /// If None, the operation must have exactly one non-dataflow port
-    /// if the operation type has other_edges, or zero otherwise.
-    pub fn non_df_port_count(&self, dir: Direction) -> Option<usize> {
-        match dir {
-            Direction::Incoming => self.non_df_ports.0,
-            Direction::Outgoing => self.non_df_ports.1,
-        }
-    }
-}
-
 impl Default for OpValidityFlags {
     fn default() -> Self {
         // Defaults to flags valid for non-container operations
@@ -65,7 +46,6 @@ impl Default for OpValidityFlags {
             allowed_second_child: OpTag::Any,
             requires_children: false,
             requires_dag: false,
-            non_df_ports: (None, None),
             edge_check: None,
         }
     }
@@ -316,16 +296,12 @@ impl ValidateOp for BasicBlock {
     /// Returns the set of allowed parent operation types.
     fn validity_flags(&self) -> OpValidityFlags {
         match self {
-            BasicBlock::DFB {
-                tuple_sum_rows: tuple_sum_variants,
-                ..
-            } => OpValidityFlags {
+            BasicBlock::DFB { .. } => OpValidityFlags {
                 allowed_children: OpTag::DataflowChild,
                 allowed_first_child: OpTag::Input,
                 allowed_second_child: OpTag::Output,
                 requires_children: true,
                 requires_dag: true,
-                non_df_ports: (None, Some(tuple_sum_variants.len())),
                 ..Default::default()
             },
             // Default flags are valid for non-container operations