diff --git a/ndc_analyser/src/analyser.rs b/ndc_analyser/src/analyser.rs
index 212af7a9..87ecf2c1 100644
--- a/ndc_analyser/src/analyser.rs
+++ b/ndc_analyser/src/analyser.rs
@@ -517,9 +517,22 @@ impl Analyser {
                 self.analyse(value)?;
             }
             Lvalue::Sequence(seq) => {
-                let sub_types = typ
-                    .unpack()
-                    .ok_or_else(|| AnalysisError::unable_to_unpack_type(&typ, span))?;
+                // If the type is a fixed-length Tuple whose arity doesn't match
+                // the number of lvalues, fall back to Any for each element. This
+                // can happen when a variable is declared with one type (e.g. ())
+                // and later reassigned to a tuple of a different arity — the
+                // analyser doesn't track reassignment types.
+                let sub_types: Box<dyn Iterator<Item = &StaticType>> =
+                    if let StaticType::Tuple(elems) = &typ {
+                        if elems.len() != seq.len() {
+                            Box::new(std::iter::repeat(&StaticType::Any))
+                        } else {
+                            Box::new(elems.iter())
+                        }
+                    } else {
+                        typ.unpack()
+                            .ok_or_else(|| AnalysisError::unable_to_unpack_type(&typ, span))?
+                    };
 
                 for (sub_lvalue, sub_lvalue_type) in seq.iter_mut().zip(sub_types) {
                     self.resolve_lvalue_declarative(
diff --git a/ndc_bin/src/highlighter.rs b/ndc_bin/src/highlighter.rs
index efdb33dc..3b7dbeae 100644
--- a/ndc_bin/src/highlighter.rs
+++ b/ndc_bin/src/highlighter.rs
@@ -1,7 +1,7 @@
+use ahash::AHashSet;
 use itertools::Itertools;
 use ndc_lexer::{Lexer, Token, TokenLocation};
 use ndc_parser::{Expression, ExpressionLocation, ForBody, ForIteration};
-use ahash::AHashSet;
 use yansi::{Paint, Painted};
 
 pub(crate) struct AndycppHighlighter;
diff --git a/tests/programs/900_bugs/bug0015_unpack_mismatched_tuple_arity.ndc b/tests/programs/900_bugs/bug0015_unpack_mismatched_tuple_arity.ndc
new file mode 100644
index 00000000..ba9120ff
--- /dev/null
+++ b/tests/programs/900_bugs/bug0015_unpack_mismatched_tuple_arity.ndc
@@ -0,0 +1,13 @@
+// Destructuring let where the variable was declared as () but later
+// reassigned to a 2-tuple should not cause a false "not declared" error.
+// expect-output: 4
+
+let pos = ();
+pos = (1, 3);
+
+fn use_pos() {
+    let a, b = pos;
+    (a + b).print;
+}
+
+use_pos();