diff --git a/helix-core/src/words.rs b/helix-core/src/words.rs
index 0099d56a..5ff25050 100644
--- a/helix-core/src/words.rs
+++ b/helix-core/src/words.rs
@@ -31,3 +31,35 @@ pub fn nth_prev_word_boundary(slice: RopeSlice, mut char_idx: usize, count: usiz
         char_idx + 1
     }
 }
+
+#[test]
+fn different_prev_word_boundary() {
+    use ropey::Rope;
+    let t = |x, y| {
+        let text = Rope::from(x);
+        let out = nth_prev_word_boundary(text.slice(..), text.len_chars() - 1, 1);
+        assert_eq!(text.slice(..out), y, r#"from "{}""#, x);
+    };
+    t("abcd\nefg\nwrs", "abcd\nefg\n");
+    t("abcd\nefg\n", "abcd\n");
+    t("abcd\n", "");
+    t("hello, world!", "hello, world");
+    t("hello, world", "hello, ");
+    t("hello, ", "hello");
+    t("hello", "");
+    t("こんにちは、世界！", "こんにちは、世界！"); // TODO: punctuation
+    t("こんにちは、世界", "こんにちは、");
+    t("こんにちは、", "こんにちは、"); // what?
+    t("こんにちは", "");
+    t("この世界。", "この世界。"); // what?
+    t("この世界", "");
+    t("お前はもう死んでいる", "");
+    t("その300円です", ""); // TODO: should stop at 300
+    t("唱k", ""); // TODO: should stop at 唱
+    t("1 + 1 = 2", "1 + 1 = ");
+    t("1 + 1 =", "1 + 1 ");
+    t("1 + 1", "1 + ");
+    t("1 + ", "1 ");
+    t("1 ", "");
+    t("1+1=2", "1+1=");
+}