diff --git a/cpp2rust/converter/rules/registry.cpp b/cpp2rust/converter/rules/registry.cpp
index 182cb1c80c..06c6d32d0a 100644
--- a/cpp2rust/converter/rules/registry.cpp
+++ b/cpp2rust/converter/rules/registry.cpp
@@ -315,8 +315,7 @@ TypeRuleMatch findType(clang::QualType use) {
   if (!best.rule_decl) {
     auto spelled = RuleDecls::SpelledTypedef(ctx, use);
     if (spelled && !IsUserDefinedDecl(spelled)) {
-      use.dump(llvm::errs(), ctx);
-      llvm::report_fatal_error("typedef has no type rule");
+      return findType(use.getCanonicalType());
     }
   }
   return best;
diff --git a/tests/unit/out/refcount/string.rs b/tests/unit/out/refcount/string.rs
index 0554bcb5ef..b8116f7f97 100644
--- a/tests/unit/out/refcount/string.rs
+++ b/tests/unit/out/refcount/string.rs
@@ -330,6 +330,10 @@ fn main_0() -> i32 {
     assert!((((elem!(output_data, 1).read()) as i32) == (('a' as i8) as i32)));
     assert!((((elem!(output_data, 2).read()) as i32) == (('s' as i8) as i32)));
     assert!((((elem!(output_data, 3).read()) as i32) == (('t' as i8) as i32)));
+    let mut diff: i64 = (-3_i32 as i64);
+    assert!((diff < 0_i64));
+    diff += 6_i64;
+    assert!((diff == 3_i64));
     let mut t0: usize = ((*s1.borrow()).len() - 1);
     let mut t1: usize = (t0).wrapping_add(((p1.read()) as usize));
     let mut t2: usize = (t1).wrapping_add(((*s2.borrow()).len() - 1));
diff --git a/tests/unit/out/unsafe/string.rs b/tests/unit/out/unsafe/string.rs
index fa864e979a..5ab22b3acc 100644
--- a/tests/unit/out/unsafe/string.rs
+++ b/tests/unit/out/unsafe/string.rs
@@ -346,6 +346,10 @@ unsafe fn main_0() -> i32 {
     assert!((((*output_data.offset((1) as isize)) as i32) == (('a' as libc::c_char) as i32)));
     assert!((((*output_data.offset((2) as isize)) as i32) == (('s' as libc::c_char) as i32)));
     assert!((((*output_data.offset((3) as isize)) as i32) == (('t' as libc::c_char) as i32)));
+    let mut diff: i64 = (-3_i32 as i64);
+    assert!(((diff) < (0_i64)));
+    diff += 6_i64;
+    assert!(((diff) == (3_i64)));
     let mut t0: usize = (s1.len() - 1);
     let mut t1: usize = (t0).wrapping_add(((*p1) as usize));
     let mut t2: usize = (t1).wrapping_add((s2.len() - 1));
diff --git a/tests/unit/string.cpp b/tests/unit/string.cpp
index 302875e956..02e70149a6 100644
--- a/tests/unit/string.cpp
+++ b/tests/unit/string.cpp
@@ -138,6 +138,10 @@ int main() {
   assert(output_data[1] == 'a');
   assert(output_data[2] == 's');
   assert(output_data[3] == 't');
+  std::string::difference_type diff = -3;
+  assert(diff < 0);
+  diff += 6;
+  assert(diff == 3);
 
   // FIXME
   auto t0 = s1.length();