diff --git a/explorer/testdata/operators/add_builtin.carbon b/explorer/testdata/operators/add_builtin.carbon
index 7a68276a6121f..e61291de95ea3 100644
--- a/explorer/testdata/operators/add_builtin.carbon
+++ b/explorer/testdata/operators/add_builtin.carbon
@@ -7,13 +7,18 @@
 // RUN: %{explorer} --parser_debug --trace_file=- %s 2>&1 | \
 // RUN:   %{FileCheck} --match-full-lines --allow-unused-prefixes %s
 // AUTOUPDATE: %{explorer} %s
-// CHECK: result: 3
+// CHECK: Interface: 5
+// CHECK: Op: 5
+// CHECK: result: 0
 
 package ExplorerTest api;
 
-// TODO: T:! Add
-fn DoAdd[T:! AddWith(.Self) where .Result == .Self](x: T, y: T) -> T { return x + y; }
-
 fn Main() -> i32 {
-  return DoAdd(1, 2);
+  var lhs: i32 = 3;
+  var rhs: i32 = 2;
+  // Make sure that both the interface and operator work with i32. These rely on
+  // builtin arithmetic more directly.
+  Print("Interface: {0}", lhs.(AddWith(i32).Op)(rhs));
+  Print("Op: {0}", lhs + rhs);
+  return 0;
 }
diff --git a/explorer/testdata/operators/mod_builtin.carbon b/explorer/testdata/operators/mod_builtin.carbon
index ae04af8fda5af..cf3f2f753ed27 100644
--- a/explorer/testdata/operators/mod_builtin.carbon
+++ b/explorer/testdata/operators/mod_builtin.carbon
@@ -7,13 +7,18 @@
 // RUN: %{explorer} --parser_debug --trace_file=- %s 2>&1 | \
 // RUN:   %{FileCheck} --match-full-lines --allow-unused-prefixes %s
 // AUTOUPDATE: %{explorer} %s
+// CHECK: Interface: 2
+// CHECK: Op: 2
 // CHECK: result: 0
 
 package ExplorerTest api;
 
-// TODO: T:! Mod
-fn DoMod[T:! ModWith(.Self) where .Result == .Self](x: T, y: T) -> T { return x % y; }
-
 fn Main() -> i32 {
-  return DoMod(4, 2);
+  var lhs: i32 = 8;
+  var rhs: i32 = 3;
+  // Make sure that both the interface and operator work with i32. These rely on
+  // builtin arithmetic more directly.
+  Print("Interface: {0}", lhs.(ModWith(i32).Op)(rhs));
+  Print("Op: {0}", lhs % rhs);
+  return 0;
 }
diff --git a/explorer/testdata/operators/mul_builtin.carbon b/explorer/testdata/operators/mul_builtin.carbon
index 2df8512560c42..563fdcc63b5b1 100644
--- a/explorer/testdata/operators/mul_builtin.carbon
+++ b/explorer/testdata/operators/mul_builtin.carbon
@@ -7,13 +7,18 @@
 // RUN: %{explorer} --parser_debug --trace_file=- %s 2>&1 | \
 // RUN:   %{FileCheck} --match-full-lines --allow-unused-prefixes %s
 // AUTOUPDATE: %{explorer} %s
-// CHECK: result: 6
+// CHECK: Interface: 6
+// CHECK: Op: 6
+// CHECK: result: 0
 
 package ExplorerTest api;
 
-// TODO: T:! Mul
-fn DoMul[T:! MulWith(.Self) where .Result == .Self](x: T, y: T) -> T { return x * y; }
-
 fn Main() -> i32 {
-  return DoMul(2, 3);
+  var lhs: i32 = 3;
+  var rhs: i32 = 2;
+  // Make sure that both the interface and operator work with i32. These rely on
+  // builtin arithmetic more directly.
+  Print("Interface: {0}", lhs.(MulWith(i32).Op)(rhs));
+  Print("Op: {0}", lhs * rhs);
+  return 0;
 }
diff --git a/explorer/testdata/operators/negate_builtin.carbon b/explorer/testdata/operators/negate_builtin.carbon
index bf8883e7a27f7..a9999d7171184 100644
--- a/explorer/testdata/operators/negate_builtin.carbon
+++ b/explorer/testdata/operators/negate_builtin.carbon
@@ -7,12 +7,17 @@
 // RUN: %{explorer} --parser_debug --trace_file=- %s 2>&1 | \
 // RUN:   %{FileCheck} --match-full-lines --allow-unused-prefixes %s
 // AUTOUPDATE: %{explorer} %s
-// CHECK: result: -3
+// CHECK: Interface: -3
+// CHECK: Op: -3
+// CHECK: result: 0
 
 package ExplorerTest api;
 
-fn DoNegate[T:! Negate where .Result == .Self](x: T) -> T { return -x; }
-
 fn Main() -> i32 {
-  return DoNegate(3);
+  var val: i32 = 3;
+  // Make sure that both the interface and operator work with i32. These rely on
+  // builtin arithmetic more directly.
+  Print("Interface: {0}", val.(Negate.Op)());
+  Print("Op: {0}", -val);
+  return 0;
 }
diff --git a/explorer/testdata/operators/sub_builtin.carbon b/explorer/testdata/operators/sub_builtin.carbon
index 181102d7281fd..b328ad394cfc2 100644
--- a/explorer/testdata/operators/sub_builtin.carbon
+++ b/explorer/testdata/operators/sub_builtin.carbon
@@ -7,13 +7,18 @@
 // RUN: %{explorer} --parser_debug --trace_file=- %s 2>&1 | \
 // RUN:   %{FileCheck} --match-full-lines --allow-unused-prefixes %s
 // AUTOUPDATE: %{explorer} %s
-// CHECK: result: 1
+// CHECK: Interface: 5
+// CHECK: Op: 5
+// CHECK: result: 0
 
 package ExplorerTest api;
 
-// TODO: T:! Sub
-fn DoSub[T:! SubWith(.Self) where .Result == .Self](x: T, y: T) -> T { return x - y; }
-
 fn Main() -> i32 {
-  return DoSub(3, 2);
+  var lhs: i32 = 8;
+  var rhs: i32 = 3;
+  // Make sure that both the interface and operator work with i32. These rely on
+  // builtin arithmetic more directly.
+  Print("Interface: {0}", lhs.(SubWith(i32).Op)(rhs));
+  Print("Op: {0}", lhs - rhs);
+  return 0;
 }