diff --git a/doc/DESIGN.md b/doc/DESIGN.md
index ccb28006..f60dbbb1 100644
--- a/doc/DESIGN.md
+++ b/doc/DESIGN.md
@@ -49,9 +49,8 @@ successors.
 
 Instructions are opaque to the allocator except for a few important
 bits: (1) `is_ret` (is a return instruction); (2) `is_branch` (is a
-branch instruction); (3) `is_call` (is a call instruction, for
-heuristic purposes only), (4) `is_move` (is a move between registers),
-and (5) a vector of Operands, covered below. Every block must end in a
+branch instruction); (3) `is_move` (is a move between registers), and
+(4) a vector of Operands, covered below. Every block must end in a
 return or branch.
 
 Both instructions and blocks are named by indices in contiguous index
diff --git a/src/fuzzing/func.rs b/src/fuzzing/func.rs
index 6151a7c7..320fe95f 100644
--- a/src/fuzzing/func.rs
+++ b/src/fuzzing/func.rs
@@ -15,7 +15,6 @@ use arbitrary::{Arbitrary, Unstructured};
 pub enum InstOpcode {
     Phi,
     Op,
-    Call,
     Ret,
     Branch,
 }
@@ -104,10 +103,6 @@ impl Function for Func {
         &self.block_params[block.index()][..]
     }
 
-    fn is_call(&self, insn: Inst) -> bool {
-        self.insts[insn.index()].op == InstOpcode::Call
-    }
-
     fn is_ret(&self, insn: Inst) -> bool {
         self.insts[insn.index()].op == InstOpcode::Ret
     }
@@ -500,11 +495,10 @@ impl Func {
                         .all(|op| !builder.f.reftype_vregs.contains(&op.vreg()))
                     && bool::arbitrary(u)?;
 
-                let op = *u.choose(&[InstOpcode::Op, InstOpcode::Call])?;
                 builder.add_inst(
                     Block::new(block),
                     InstData {
-                        op,
+                        op: InstOpcode::Op,
                         operands,
                         clobbers,
                         is_safepoint,
diff --git a/src/ion/dump.rs b/src/ion/dump.rs
index 0048f801..e7a8ed75 100644
--- a/src/ion/dump.rs
+++ b/src/ion/dump.rs
@@ -103,8 +103,6 @@ impl<'a, F: Function> Env<'a, F> {
                     .collect::<Vec<_>>();
                 let opname = if self.func.is_branch(inst) {
                     "br"
-                } else if self.func.is_call(inst) {
-                    "call"
                 } else if self.func.is_ret(inst) {
                     "ret"
                 } else {
diff --git a/src/lib.rs b/src/lib.rs
index 19809089..dcc231a7 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -847,10 +847,6 @@ pub trait Function {
     /// Get the block parameters for a given block.
     fn block_params(&self, block: Block) -> &[VReg];
 
-    /// Determine whether an instruction is a call instruction. This is used
-    /// only for splitting heuristics.
-    fn is_call(&self, insn: Inst) -> bool;
-
     /// Determine whether an instruction is a return instruction.
     fn is_ret(&self, insn: Inst) -> bool;