diff --git a/libs/wpp/wpp.c b/libs/wpp/wpp.c
index ec70e873f89..d7b2dc842ce 100644
--- a/libs/wpp/wpp.c
+++ b/libs/wpp/wpp.c
@@ -28,7 +28,7 @@
 #include "wpp_private.h"
 #include "wine/wpp.h"
 
-int ppdebug;
+int ppdebug, pp_flex_debug;
 
 struct define
 {
diff --git a/tools/widl/widl.c b/tools/widl/widl.c
index 2c4a3c6cee5..02e7eeebee5 100644
--- a/tools/widl/widl.c
+++ b/tools/widl/widl.c
@@ -80,6 +80,7 @@ static const char version_string[] = "Wine IDL Compiler version " PACKAGE_VERSIO
 
 int win32 = 1;
 int debuglevel = DEBUGLEVEL_NONE;
+int yy_flex_debug;
 
 int pedantic = 0;
 static int do_everything = 1;
diff --git a/tools/wrc/wrc.c b/tools/wrc/wrc.c
index 394efb09633..679f0cd1e25 100644
--- a/tools/wrc/wrc.c
+++ b/tools/wrc/wrc.c
@@ -166,6 +166,8 @@ int char_number = 1;		/* The current char pos within the line */
 char *cmdline;			/* The entire commandline */
 time_t now;			/* The time of start of wrc */
 
+int yy_flex_debug;
+
 resource_t *resource_top;	/* The top of the parsed resources */
 
 int getopt (int argc, char *const *argv, const char *optstring);