diff --git a/compiler/can/src/builtins.rs b/compiler/can/src/builtins.rs
index 910ff0b1f7..9bc853cdc0 100644
--- a/compiler/can/src/builtins.rs
+++ b/compiler/can/src/builtins.rs
@@ -100,6 +100,36 @@ pub fn builtin_defs(var_store: &mut VarStore) -> MutMap<Symbol, Def> {
         Symbol::NUM_ATAN => num_atan,
         Symbol::NUM_ACOS => num_acos,
         Symbol::NUM_ASIN => num_asin,
+        Symbol::NUM_MAX_INT => num_max_int,
+        Symbol::NUM_MIN_INT => num_min_int,
+    }
+}
+
+/// Num.maxInt : Int
+fn num_max_int(symbol: Symbol, var_store: &mut VarStore) -> Def {
+    let int_var = var_store.fresh();
+    let body = Int(int_var, i64::MAX);
+
+    Def {
+        annotation: None,
+        expr_var: int_var,
+        loc_expr: Located::at_zero(body),
+        loc_pattern: Located::at_zero(Pattern::Identifier(symbol)),
+        pattern_vars: SendMap::default(),
+    }
+}
+
+/// Num.minInt : Int
+fn num_min_int(symbol: Symbol, var_store: &mut VarStore) -> Def {
+    let int_var = var_store.fresh();
+    let body = Int(int_var, i64::MIN);
+
+    Def {
+        annotation: None,
+        expr_var: int_var,
+        loc_expr: Located::at_zero(body),
+        loc_pattern: Located::at_zero(Pattern::Identifier(symbol)),
+        pattern_vars: SendMap::default(),
     }
 }
 
diff --git a/compiler/gen/tests/gen_num.rs b/compiler/gen/tests/gen_num.rs
index 4da085eac0..8c9a41374a 100644
--- a/compiler/gen/tests/gen_num.rs
+++ b/compiler/gen/tests/gen_num.rs
@@ -794,11 +794,23 @@ mod gen_num {
         assert_evals_to!(
             indoc!(
                 r#"
-                # Num.maxInt
-                Num.add (-1) Num.maxInt
+                Num.maxInt
                 "#
             ),
-            1,
+            i64::MAX,
+            i64
+        );
+    }
+
+    #[test]
+    fn num_min_int() {
+        assert_evals_to!(
+            indoc!(
+                r#"
+                Num.minInt
+                "#
+            ),
+            i64::MIN,
             i64
         );
     }
diff --git a/compiler/mono/src/ir.rs b/compiler/mono/src/ir.rs
index 9e75a00495..6f801fedbd 100644
--- a/compiler/mono/src/ir.rs
+++ b/compiler/mono/src/ir.rs
@@ -2029,6 +2029,20 @@ pub fn with_hole<'a>(
                     env.arena.alloc(Stmt::Ret(assigned)),
                 );
 
+                return result;
+            } else if symbol.module_id() != env.home {
+                // TODO here we assume this is a 0-arity thunk. That's not true in general!
+                let result = call_by_name(
+                    env,
+                    procs,
+                    variable,
+                    symbol,
+                    std::vec::Vec::new(),
+                    layout_cache,
+                    assigned,
+                    env.arena.alloc(Stmt::Ret(assigned)),
+                );
+                dbg!(&procs.externals_we_need);
                 return result;
             }