diff --git a/libs/util/cexpr-lex.l b/libs/util/cexpr-lex.l
index 0bb03246d..2c696dfee 100644
--- a/libs/util/cexpr-lex.l
+++ b/libs/util/cexpr-lex.l
@@ -55,8 +55,10 @@
 #include "QF/cexpr.h"
 #include "libs/util/cexpr-parse.h"
 
-#define YY_NO_INPUT
-#define YY_NO_UNPUT
+#define YY_NO_INPUT	// debian flex
+#define YY_NO_UNPUT	// debian flex
+#define YY_NO_YYINPUT
+#define YY_NO_YYUNPUT
 
 #define YYSTYPE CEXPR_YYSTYPE
 #define YY_EXTRA_TYPE exprctx_t *
diff --git a/tools/qfcc/source/qc-lex.l b/tools/qfcc/source/qc-lex.l
index cced3d5a4..bbe3a8353 100644
--- a/tools/qfcc/source/qc-lex.l
+++ b/tools/qfcc/source/qc-lex.l
@@ -75,8 +75,10 @@
 # define YY_FLEX_REALLOC_HACK
 #endif
 
-#define YY_NO_INPUT
-#define YY_NO_UNPUT
+#define YY_NO_INPUT	// debian flex
+#define YY_NO_UNPUT	// debian flex
+#define YY_NO_YYINPUT
+#define YY_NO_YYUNPUT
 
 #define YYSTYPE QC_YYSTYPE
 #define YYLTYPE QC_YYLTYPE
@@ -139,7 +141,7 @@ STRING		\"(\\.|[^"\\])*\"
 %x		GRAB_FRAME GRAB_OTHER GRAB_WRITE COMMENT LCOMMENT PRAGMA
 
 %%
-					yy_flex_debug = 0;
+					yyset_debug (0, yyscanner);
 					grab_frame = GRAB_FRAME;
 					grab_other = GRAB_OTHER;
 					grab_write = GRAB_WRITE;
diff --git a/tools/qfcc/source/qp-lex.l b/tools/qfcc/source/qp-lex.l
index 4ca8d11bb..0bf98ef2c 100644
--- a/tools/qfcc/source/qp-lex.l
+++ b/tools/qfcc/source/qp-lex.l
@@ -60,8 +60,10 @@
 # define YY_FLEX_REALLOC_HACK
 #endif
 
-#define YY_NO_INPUT
-#define YY_NO_UNPUT
+#define YY_NO_INPUT	// debian flex
+#define YY_NO_UNPUT	// debian flex
+#define YY_NO_YYINPUT
+#define YY_NO_YYUNPUT
 
 
 #define YYSTYPE QP_YYSTYPE