diff --git a/Cargo.toml b/Cargo.toml
index 6a8c558..0c99c74 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "dtoa-short"
-version = "0.3.0"
+version = "0.3.1"
 authors = ["Xidorn Quan <me@upsuper.org>"]
 
 description = "Serialize float number and truncate to certain precision"
diff --git a/src/lib.rs b/src/lib.rs
index a0b5fa0..5270377 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -68,7 +68,7 @@ fn write_with_prec<W, V>(dest: &mut W, value: V, prec: usize)
 
 fn restrict_prec(buf: &mut [u8], prec: usize) -> (&[u8], Notation) {
     let len = buf.len();
-    debug_assert!(len <= BUFFER_SIZE, "dtoa may have changed its buffer size");
+    debug_assert!(len <= BUFFER_SIZE + 1, "dtoa may have changed its buffer size");
     // Put a leading zero to capture any carry.
     debug_assert!(buf[0] == b'\0', "Caller must prepare an empty byte for us");
     buf[0] = b'0';
diff --git a/tests/basic.rs b/tests/basic.rs
index a47141e..9244669 100644
--- a/tests/basic.rs
+++ b/tests/basic.rs
@@ -132,4 +132,6 @@ fn exponent_part_handling() {
     assert_expected_serialization(-9.999999e30_f32, "-10e30");
     assert_expected_serialization(9.999999e-30_f32, "10e-30");
     assert_expected_serialization(-9.999999e-30_f32, "-10e-30");
+    // Regression test for assertion failure (https://bugzilla.mozilla.org/show_bug.cgi?id=1402419)
+    assert_expected_serialization(-8192e17_f32, "-819200000000000000000");
 }