diff --git a/epan/dfilter/dfilter.c b/epan/dfilter/dfilter.c
index c3cc4017b2..ea57e4735a 100644
--- a/epan/dfilter/dfilter.c
+++ b/epan/dfilter/dfilter.c
@@ -413,20 +413,20 @@ dfilter_compile_real(const gchar *text, dfilter_t **dfp,
 		ws_noisy("Verbatim text: %s", dfw->expanded_text);
 	}
 
-	if (df_lex_init(&scanner) != 0) {
+	if (df_yylex_init(&scanner) != 0) {
 		dfw_error_set_msg(errpp, "Can't initialize scanner: %s", g_strerror(errno));
 		goto FAILURE;
 	}
 
-	in_buffer = df__scan_string(dfw->expanded_text, scanner);
+	in_buffer = df_yy_scan_string(dfw->expanded_text, scanner);
 
 	memset(&state, 0, sizeof(state));
 	state.dfw = dfw;
 
-	df_set_extra(&state, scanner);
+	df_yyset_extra(&state, scanner);
 
 	/* Enable/disable debugging for Flex. */
-	df_set_debug(flags & DF_DEBUG_FLEX, scanner);
+	df_yyset_debug(flags & DF_DEBUG_FLEX, scanner);
 
 #ifndef NDEBUG
 	/* Enable/disable debugging for Lemon. */
@@ -439,7 +439,7 @@ dfilter_compile_real(const gchar *text, dfilter_t **dfp,
 
 	while (1) {
 		df_lval = stnode_new_empty(STTYPE_UNINITIALIZED);
-		token = df_lex(scanner);
+		token = df_yylex(scanner);
 
 		/* Check for scanner failure */
 		if (token == SCAN_FAILED) {
@@ -492,8 +492,8 @@ dfilter_compile_real(const gchar *text, dfilter_t **dfp,
 	/* Free scanner state */
 	if (state.quoted_string != NULL)
 		g_string_free(state.quoted_string, TRUE);
-	df__delete_buffer(in_buffer, scanner);
-	df_lex_destroy(scanner);
+	df_yy_delete_buffer(in_buffer, scanner);
+	df_yylex_destroy(scanner);
 
 	if (failure)
 		goto FAILURE;
diff --git a/epan/dfilter/scanner.l b/epan/dfilter/scanner.l
index 3a8d2c789b..117bfec7fe 100644
--- a/epan/dfilter/scanner.l
+++ b/epan/dfilter/scanner.l
@@ -46,10 +46,10 @@
 %option never-interactive
 
 /*
- * Prefix scanner routines with "df_" rather than "yy", so this scanner
+ * Prefix scanner routines with "df_yy" rather than "yy", so this scanner
  * can coexist with other scanners.
  */
-%option prefix="df_"
+%option prefix="df_yy"
 
 /*
  * We're reading from a string, so we don't need yywrap.
@@ -61,19 +61,6 @@
  */
 %option extra-type="df_scanner_state_t *"
 
-/*
- * We have to override the memory allocators so that we don't get
- * "unused argument" warnings from the yyscanner argument (which
- * we don't use, as we have a global memory allocator).
- *
- * We provide, as macros, our own versions of the routines generated by Flex,
- * which just call malloc()/realloc()/free() (as the Flex versions do),
- * discarding the extra argument.
- */
-%option noyyalloc
-%option noyyrealloc
-%option noyyfree
-
 %{
 /*
  * Wireshark - Network traffic analyzer
@@ -116,18 +103,6 @@ static void update_string_loc(df_scanner_state_t *state, const char *text);
 		dfilter_fail(yyextra->dfw, DF_ERROR_GENERIC, yyextra->location, __VA_ARGS__); \
 	} while (0)
 
-/*
- * Sleazy hack to suppress compiler warnings in yy_fatal_error().
- */
-#define YY_EXIT_FAILURE ((void)yyscanner, 2)
-
-/*
- * Macros for the allocators, to discard the extra argument.
- */
-#define df_alloc(size, yyscanner)		(void *)malloc(size)
-#define df_realloc(ptr, size, yyscanner)	(void *)realloc((char *)(ptr), (size))
-#define df_free(ptr, yyscanner)			free((char *)ptr)
-
 %}
 
 Identifier	[[:alnum:]_][[:alnum:]_-]*(\.[[:alnum:]_-]+)*