diff --git a/backup.go b/backup.go
index fe726f2..d4a6719 100644
--- a/backup.go
+++ b/backup.go
@@ -1,6 +1,6 @@
 package sqlite3
 
-// Backup is a handle to an open BLOB.
+// Backup is an handle to an ongoing online backup operation.
 //
 // https://www.sqlite.org/c3ref/backup.html
 type Backup struct {
diff --git a/blob.go b/blob.go
index a6dc88b..3ff9416 100644
--- a/blob.go
+++ b/blob.go
@@ -11,7 +11,7 @@ import (
 // [database/sql.DB.Exec] and similar methods.
 type ZeroBlob int64
 
-// Blob is a handle to an open BLOB.
+// Blob is an handle to an open BLOB.
 //
 // It implements [io.ReadWriteSeeker] for incremental BLOB I/O.
 //
diff --git a/sqlite3/os.c b/sqlite3/os.c
index 4771573..ccb21c5 100644
--- a/sqlite3/os.c
+++ b/sqlite3/os.c
@@ -37,7 +37,6 @@ int os_unlock(sqlite3_file *, int eLock);
 int os_check_reserved_lock(sqlite3_file *, int *pResOut);
 
 static int os_file_control_w(sqlite3_file *file, int op, void *pArg) {
-  struct os_file *pFile = (struct os_file *)file;
   if (op == SQLITE_FCNTL_VFSNAME) {
     *(char **)pArg = sqlite3_mprintf("%s", "os");
     return SQLITE_OK;
diff --git a/sqlite3/sqlite_cfg.h b/sqlite3/sqlite_cfg.h
index 3b65eb5..ec69dac 100644
--- a/sqlite3/sqlite_cfg.h
+++ b/sqlite3/sqlite_cfg.h
@@ -55,5 +55,5 @@
 // #define SQLITE_ENABLE_SESSION 1
 // #define SQLITE_ENABLE_PREUPDATE_HOOK 1
 
-// Implemented in Go.
+// Implemented in os.c.
 int localtime_s(struct tm *const pTm, time_t const *const pTime);
\ No newline at end of file