diff --git a/configure.ac b/configure.ac
index 80a0302..fd56e68 100644
--- a/configure.ac
+++ b/configure.ac
@@ -61,7 +61,7 @@ AM_CONDITIONAL(SQL, test x$sql = xtrue)
 AC_SUBST(SQL)
 AC_SUBST(LFLAGS)
 
-CFLAGS="$CFLAGS -Wall"
+CFLAGS="$CFLAGS -Wall -Wstrict-prototypes"
 dnl Enable -Wl,--as-needed by default to prevent overlinking
 
 AC_ARG_ENABLE([as-needed],
diff --git a/include/mdbsql.h b/include/mdbsql.h
index 8dae1be..951a340 100644
--- a/include/mdbsql.h
+++ b/include/mdbsql.h
@@ -77,8 +77,8 @@ extern char *g_input_ptr;
 
 void mdb_sql_error(MdbSQL* sql, char *fmt, ...);
 extern MdbSQL *_mdb_sql(MdbSQL *sql);
-extern MdbSQL *mdb_sql_init();
-extern MdbSQLSarg *mdb_sql_alloc_sarg();
+extern MdbSQL *mdb_sql_init(void);
+extern MdbSQLSarg *mdb_sql_alloc_sarg(void);
 extern MdbHandle *mdb_sql_open(MdbSQL *sql, char *db_name);
 extern int mdb_sql_add_sarg(MdbSQL *sql, char *col_name, int op, char *constant);
 extern void mdb_sql_all_columns(MdbSQL *sql);
diff --git a/include/mdbtools.h b/include/mdbtools.h
index 651b390..d2fc942 100644
--- a/include/mdbtools.h
+++ b/include/mdbtools.h
@@ -436,8 +436,8 @@ typedef struct {
 } MdbSarg;
 
 /* mem.c */
-extern MDB_DEPRECATED(void, mdb_init());
-extern MDB_DEPRECATED(void, mdb_exit());
+extern MDB_DEPRECATED(void, mdb_init(void));
+extern MDB_DEPRECATED(void, mdb_exit(void));
 
 /* file.c */
 extern ssize_t mdb_read_pg(MdbHandle *mdb, unsigned long pg);
@@ -502,7 +502,7 @@ extern size_t mdb_ole_read_next(MdbHandle *mdb, MdbColumn *col, void *ole_ptr);
 extern size_t mdb_ole_read(MdbHandle *mdb, MdbColumn *col, void *ole_ptr, int chunk_size);
 extern void* mdb_ole_read_full(MdbHandle *mdb, MdbColumn *col, size_t *size);
 extern void mdb_set_date_fmt(const char *);
-extern void mdb_set_boolean_fmt_words();
+extern void mdb_set_boolean_fmt_words(void);
 extern int mdb_read_row(MdbTableDef *table, unsigned int row);
 
 /* dump.c */
@@ -514,9 +514,9 @@ extern MDB_DEPRECATED(int, mdb_coltype_takes_length(MdbBackend *backend, int col
 extern const MdbBackendType* mdb_get_colbacktype(const MdbColumn *col);
 extern const char* mdb_get_colbacktype_string(const MdbColumn *col);
 extern int mdb_colbacktype_takes_length(const MdbColumn *col);
-extern MDB_DEPRECATED(void, mdb_init_backends());
+extern MDB_DEPRECATED(void, mdb_init_backends(void));
 extern void mdb_register_backend(char *backend_name, guint32 capabilities, MdbBackendType *backend_type, MdbBackendType *type_shortdate, MdbBackendType *type_autonum, const char *short_now, const char *long_now, const char *charset_statement, const char *drop_statement, const char *constaint_not_empty_statement, const char *column_comment_statement, const char *table_comment_statement, gchar* (*quote_schema_name)(const gchar*, const gchar*));
-extern MDB_DEPRECATED(void, mdb_remove_backends());
+extern MDB_DEPRECATED(void, mdb_remove_backends(void));
 extern int  mdb_set_default_backend(MdbHandle *mdb, const char *backend_name);
 extern void mdb_print_schema(MdbHandle *mdb, FILE *outfile, char *tabname, char *dbnamespace, guint32 export_options);
 
diff --git a/src/libmdb/backend.c b/src/libmdb/backend.c
index 869994d..c67c0ba 100644
--- a/src/libmdb/backend.c
+++ b/src/libmdb/backend.c
@@ -35,7 +35,7 @@
 
 static int is_init;
 GHashTable *mdb_backends;
-void _mdb_remove_backends();
+void _mdb_remove_backends(void);
 
 /*    Access data types */
 static MdbBackendType mdb_access_types[] = {
diff --git a/src/libmdb/options.c b/src/libmdb/options.c
index c165e7b..2ae9f12 100644
--- a/src/libmdb/options.c
+++ b/src/libmdb/options.c
@@ -31,7 +31,7 @@
 static unsigned long opts;
 static int optset;
 
-static void load_options();
+static void load_options(void);
 
 void
 mdb_debug(int klass, char *fmt, ...)