diff --git a/configure b/configure
index a82dcdcff0..0446c45718 100755
--- a/configure
+++ b/configure
@@ -18374,7 +18374,7 @@ if ac_fn_c_try_compile "$LINENO"; then :
 $as_echo "yes" >&6; }
 	AST_ADDRESS_SANITIZER=1
 else
-  AST_ADDRESS_SANITIZER=
+  AST_ADDRESS_SANITIZER=0
 	{ $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
 $as_echo "no" >&6; }
 
@@ -18406,7 +18406,7 @@ if ac_fn_c_try_compile "$LINENO"; then :
 $as_echo "yes" >&6; }
 	AST_THREAD_SANITIZER=1
 else
-  AST_THREAD_SANITIZER=
+  AST_THREAD_SANITIZER=0
 	{ $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
 $as_echo "no" >&6; }
 
diff --git a/configure.ac b/configure.ac
index 42320e4f26..e4a20cfa5a 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1106,7 +1106,7 @@ AC_COMPILE_IFELSE(
 	[AC_LANG_PROGRAM([], [int x = 1;])],
 	AC_MSG_RESULT(yes)
 	[AST_ADDRESS_SANITIZER=1],
-	[AST_ADDRESS_SANITIZER=]
+	[AST_ADDRESS_SANITIZER=0]
 	AC_MSG_RESULT(no)
 )
 CFLAGS="${saved_sanitize_CFLAGS}"
@@ -1122,7 +1122,7 @@ AC_COMPILE_IFELSE(
 	[AC_LANG_PROGRAM([], [int x = 1;])],
 	AC_MSG_RESULT(yes)
 	[AST_THREAD_SANITIZER=1],
-	[AST_THREAD_SANITIZER=]
+	[AST_THREAD_SANITIZER=0]
 	AC_MSG_RESULT(no)
 )
 CFLAGS="${saved_sanitize_CFLAGS}"