diff --git a/lib/libc/tests/secure/fortify_uio_test.c b/lib/libc/tests/secure/fortify_uio_test.c
index 46b46ed2f7d..b1b51eff824 100644
--- a/lib/libc/tests/secure/fortify_uio_test.c
+++ b/lib/libc/tests/secure/fortify_uio_test.c
@@ -179,6 +179,8 @@ ATF_TC_BODY(readv_before_end, tc)
 	const size_t __len = 2 - 1;
 	const size_t __idx __unused = __len - 1;
 
+	replace_stdin();
+
 	readv(STDIN_FILENO, __stack.__buf, __len);
 #undef BUF
 
@@ -200,6 +202,8 @@ ATF_TC_BODY(readv_end, tc)
 	const size_t __len = 2;
 	const size_t __idx __unused = __len - 1;
 
+	replace_stdin();
+
 	readv(STDIN_FILENO, __stack.__buf, __len);
 #undef BUF
 
@@ -230,6 +234,8 @@ ATF_TC_BODY(readv_after_end, tc)
 
 	/* Child */
 	disable_coredumps();
+	replace_stdin();
+
 	readv(STDIN_FILENO, __stack.__buf, __len);
 	_exit(EX_SOFTWARE);	/* Should have aborted. */
 
@@ -274,6 +280,7 @@ ATF_TC_BODY(readv_heap_before_end, tc)
 	const size_t __idx __unused = __len - 1;
 
 	__stack.__buf = malloc(__bufsz);
+	replace_stdin();
 
 	readv(STDIN_FILENO, __stack.__buf, __len);
 #undef BUF
@@ -297,6 +304,7 @@ ATF_TC_BODY(readv_heap_end, tc)
 	const size_t __idx __unused = __len - 1;
 
 	__stack.__buf = malloc(__bufsz);
+	replace_stdin();
 
 	readv(STDIN_FILENO, __stack.__buf, __len);
 #undef BUF
@@ -329,6 +337,7 @@ ATF_TC_BODY(readv_heap_after_end, tc)
 	/* Child */
 	disable_coredumps();
 	__stack.__buf = malloc(__bufsz);
+	replace_stdin();
 
 	readv(STDIN_FILENO, __stack.__buf, __len);
 	_exit(EX_SOFTWARE);	/* Should have aborted. */
@@ -542,6 +551,8 @@ ATF_TC_BODY(preadv_before_end, tc)
 	const size_t __len = 2 - 1;
 	const size_t __idx __unused = __len - 1;
 
+	replace_stdin();
+
 	preadv(STDIN_FILENO, __stack.__buf, __len, 0);
 #undef BUF
 
@@ -563,6 +574,8 @@ ATF_TC_BODY(preadv_end, tc)
 	const size_t __len = 2;
 	const size_t __idx __unused = __len - 1;
 
+	replace_stdin();
+
 	preadv(STDIN_FILENO, __stack.__buf, __len, 0);
 #undef BUF
 
@@ -593,6 +606,8 @@ ATF_TC_BODY(preadv_after_end, tc)
 
 	/* Child */
 	disable_coredumps();
+	replace_stdin();
+
 	preadv(STDIN_FILENO, __stack.__buf, __len, 0);
 	_exit(EX_SOFTWARE);	/* Should have aborted. */
 
@@ -637,6 +652,7 @@ ATF_TC_BODY(preadv_heap_before_end, tc)
 	const size_t __idx __unused = __len - 1;
 
 	__stack.__buf = malloc(__bufsz);
+	replace_stdin();
 
 	preadv(STDIN_FILENO, __stack.__buf, __len, 0);
 #undef BUF
@@ -660,6 +676,7 @@ ATF_TC_BODY(preadv_heap_end, tc)
 	const size_t __idx __unused = __len - 1;
 
 	__stack.__buf = malloc(__bufsz);
+	replace_stdin();
 
 	preadv(STDIN_FILENO, __stack.__buf, __len, 0);
 #undef BUF
@@ -692,6 +709,7 @@ ATF_TC_BODY(preadv_heap_after_end, tc)
 	/* Child */
 	disable_coredumps();
 	__stack.__buf = malloc(__bufsz);
+	replace_stdin();
 
 	preadv(STDIN_FILENO, __stack.__buf, __len, 0);
 	_exit(EX_SOFTWARE);	/* Should have aborted. */
diff --git a/lib/libc/tests/secure/generate-fortify-tests.lua b/lib/libc/tests/secure/generate-fortify-tests.lua
index c9cd9353a86..ef34fb8513c 100755
--- a/lib/libc/tests/secure/generate-fortify-tests.lua
+++ b/lib/libc/tests/secure/generate-fortify-tests.lua
@@ -411,6 +411,7 @@ local all_tests = {
 				"__buf",
 				"__len",
 			},
+			init = stdio_init,
 		},
 		{
 			func = "readv",
@@ -435,6 +436,7 @@ local all_tests = {
 				"__len",
 				"0",
 			},
+			init = stdio_init,
 		},
 		{
 			func = "preadv",