diff --git a/configure b/configure
index 62e0c884a2b..b09703e6c44 100755
--- a/configure
+++ b/configure
@@ -149,6 +149,8 @@ try_cflag -Wshadow-compatible-local
 
 try_cflag -Werror=incompatible-pointer-types
 
+try_cflag -fno-common
+
 if test $debug = 1
 then
 	try_cflag -g
diff --git a/src/cc1/test.c b/src/cc1/test.c
index 2eab92c9df8..b686a8e986f 100644
--- a/src/cc1/test.c
+++ b/src/cc1/test.c
@@ -23,13 +23,11 @@ enum debug_level cc1_gdebug = DEBUG_OFF;
 int cc1_gdebug_columninfo;
 int cc1_mstack_align;
 enum c_std cc1_std = STD_C99;
-struct cc1_warning cc1_warning;
 struct cc1_output cc1_output;
 dynmap *cc1_outsections;
 struct cc1_fopt cc1_fopt;
 enum mopt mopt_mode;
 int show_current_line;
-char *cc1_sanitize_handler_fn;
 enum visibility cc1_visibility_default;
 struct target_details cc1_target_details;
 enum stringop_strategy cc1_mstringop_strategy = STRINGOP_STRATEGY_THRESHOLD;