diff --git a/ext/sqlite3/libsqlite/sqlite3.c b/ext/sqlite3/libsqlite/sqlite3.c
index da0d008d222..83bd8bf6401 100644
--- a/ext/sqlite3/libsqlite/sqlite3.c
+++ b/ext/sqlite3/libsqlite/sqlite3.c
@@ -7655,6 +7655,7 @@ SQLITE_PRIVATE void sqlite3PCacheSetDefault(void);
 # define SQLITE_OS_WINCE 0
 #endif
 
+#include <ctype.h>
 
 /*
 ** Define the maximum size of a temporary filename