diff --git a/all_test.go b/all_test.go
index 4770e3e..9c869bb 100644
--- a/all_test.go
+++ b/all_test.go
@@ -1880,7 +1880,7 @@ func TestIssue66(t *testing.T) {
 		// think that's correct (jnml).
 
 		t.Logf("insert 2: %v", err)
-		if !strings.Contains(err.Error(), "SQLITE_BUSY") {
+		if !strings.Contains(err.Error(), "database is locked (5) (SQLITE_BUSY)") {
 			t.Fatalf("insert 2: %v", err)
 		}
 	}
@@ -2010,3 +2010,58 @@ func testIssue65(t *testing.T, db *sql.DB, canFail bool) {
 		}
 	}
 }
+
+// https://gitlab.com/cznic/sqlite/-/issues/73
+func TestConstraintPrimaryKeyError(t *testing.T) {
+	db, err := sql.Open(driverName, "file::memory:")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer db.Close()
+
+	_, err = db.Exec(`CREATE TABLE IF NOT EXISTS hash (hashval TEXT PRIMARY KEY NOT NULL)`)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	_, err = db.Exec("INSERT INTO hash (hashval) VALUES (?)", "somehashval")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	_, err = db.Exec("INSERT INTO hash (hashval) VALUES (?)", "somehashval")
+	if err == nil {
+		t.Fatal("wanted error")
+	}
+
+	if errs, want := err.Error(), "constraint failed: UNIQUE constraint failed: hash.hashval (1555)"; errs != want {
+		t.Fatalf("got error string %q, want %q", errs, want)
+	}
+}
+
+func TestConstraintUniqueError(t *testing.T) {
+	db, err := sql.Open(driverName, "file::memory:")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer db.Close()
+
+	_, err = db.Exec(`CREATE TABLE IF NOT EXISTS hash (hashval TEXT UNIQUE)`)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	_, err = db.Exec("INSERT INTO hash (hashval) VALUES (?)", "somehashval")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	_, err = db.Exec("INSERT INTO hash (hashval) VALUES (?)", "somehashval")
+	if err == nil {
+		t.Fatal("wanted error")
+	}
+
+	if errs, want := err.Error(), "constraint failed: UNIQUE constraint failed: hash.hashval (2067)"; errs != want {
+		t.Fatalf("got error string %q, want %q", errs, want)
+	}
+}
diff --git a/sqlite.go b/sqlite.go
index ccf079e..5383d12 100644
--- a/sqlite.go
+++ b/sqlite.go
@@ -11,7 +11,6 @@ import (
 	"context"
 	"database/sql"
 	"database/sql/driver"
-	"errors"
 	"fmt"
 	"io"
 	"math"
@@ -883,7 +882,7 @@ func (c *conn) step(pstmt uintptr) (int, error) {
 
 			return int(rc), nil
 		default:
-			return int(rc), errors.New(ErrorCodeString[int(rc)])
+			return int(rc), c.errstr(rc)
 		}
 	}
 }
@@ -1225,11 +1224,15 @@ func (c *conn) errstr(rc int32) error {
 	p := sqlite3.Xsqlite3_errstr(c.tls, rc)
 	str := libc.GoString(p)
 	p = sqlite3.Xsqlite3_errmsg(c.tls, c.db)
+	var s string
+	if rc == sqlite3.SQLITE_BUSY {
+		s = " (SQLITE_BUSY)"
+	}
 	switch msg := libc.GoString(p); {
 	case msg == str:
-		return &Error{msg: fmt.Sprintf("%s (%v)", str, rc), code: int(rc)}
+		return &Error{msg: fmt.Sprintf("%s (%v)%s", str, rc, s), code: int(rc)}
 	default:
-		return &Error{msg: fmt.Sprintf("%s: %s (%v)", str, msg, rc), code: int(rc)}
+		return &Error{msg: fmt.Sprintf("%s: %s (%v)%s", str, msg, rc, s), code: int(rc)}
 	}
 }