diff --git a/glean/rts/string.cpp b/glean/rts/string.cpp
index 83656f946..3cd258057 100644
--- a/glean/rts/string.cpp
+++ b/glean/rts/string.cpp
@@ -50,7 +50,7 @@ size_t untrustedChunks(folly::ByteRange range, Chunk&& chunk) {
 
   int k = 0;
   while (true) {
-    UChar c;
+    UChar32 c;
     // NOTE: U8_NEXT returns c<0 on overlong (invalid) points so this doesn't
     // transcode (and we don't have to worry about, say, overlong \NUL).
     U8_NEXT(p, i, size, c);
diff --git a/glean/test/tests/EncodingTest.hs b/glean/test/tests/EncodingTest.hs
index 4097a2f6b..5005cc3f8 100644
--- a/glean/test/tests/EncodingTest.hs
+++ b/glean/test/tests/EncodingTest.hs
@@ -61,7 +61,7 @@ kitchenSink = KitchenSink
       [0,0xF6,0x12345,0x65434567,minBound,maxBound]
   , kitchenSink_array_of_bool = [True,False,True]
   , kitchenSink_array_of_string =
-      ["abcd","","lzdkfhlsadhgl","asfdfs\0fasasfda\0faaf"]
+      ["abcd","","lzdkfhlsadhgl","asfdfs\0fasasfda\0faaf", "𐀀" ]
   , kitchenSink_array_of_pred =
       [ Glean.Test.Predicate 5432 Nothing
       , Glean.Test.Predicate 0x1234567 Nothing ]