diff --git a/cruciverb-core/src/error.rs b/cruciverb-core/src/error.rs
new file mode 100644
index 0000000..9967757
--- /dev/null
+++ b/cruciverb-core/src/error.rs
@@ -0,0 +1,30 @@
+use thiserror::Error;
+
+#[derive(Debug, Error)]
+pub enum CrucivError {
+    #[error("{0}")]
+    Generation(String),
+
+    #[error("Generation timed out - try a smaller grid or lower fill percentage")]
+    Timeout(u64),
+
+    #[error("invalid grid: {0}")]
+    InvalidGrid(String),
+
+    #[error("validation failed: {0}")]
+    Validation(String),
+
+    #[error("dictionary error: {0}")]
+    Dictionary(String),
+
+    #[error("no clue found for word: {0}")]
+    MissingClue(String),
+
+    #[error(transparent)]
+    Io(#[from] std::io::Error),
+
+    #[error(transparent)]
+    Json(#[from] serde_json::Error),
+}
+
+pub type Result<T> = std::result::Result<T, CrucivError>;