diff --git a/tests/data/test2502 b/tests/data/test2502
index 2efd04f2d0..7a9756a69d 100644
--- a/tests/data/test2502
+++ b/tests/data/test2502
@@ -59,7 +59,7 @@ lib%TESTNUMBER
 HTTP GET multiple over HTTP/3
 </name>
 <command>
-https://%HOSTIP:%HTTP3PORT/path/%TESTNUMBER %HOSTIP %HTTP3PORT
+https://%HOSTIP:%HTTP3PORT/path/%TESTNUMBER %HOSTIP %HTTP3PORT %SRCDIR/certs/EdelCurlRoot-ca.cacert
 </command>
 </client>
 
diff --git a/tests/libtest/first.c b/tests/libtest/first.c
index e098a744f1..a70fd54e5f 100644
--- a/tests/libtest/first.c
+++ b/tests/libtest/first.c
@@ -75,6 +75,7 @@ void wait_ms(int ms)
 
 char *libtest_arg2 = NULL;
 char *libtest_arg3 = NULL;
+char *libtest_arg4 = NULL;
 int test_argc;
 char **test_argv;
 
@@ -201,6 +202,9 @@ int main(int argc, char **argv)
   if(argc > (basearg + 2))
     libtest_arg3 = argv[basearg + 2];
 
+  if(argc > (basearg + 2))
+    libtest_arg4 = argv[basearg + 3];
+
   URL = argv[basearg]; /* provide this to the rest */
 
   fprintf(stderr, "URL: %s\n", URL);
diff --git a/tests/libtest/lib2502.c b/tests/libtest/lib2502.c
index f01fbe0c5c..340d0bf550 100644
--- a/tests/libtest/lib2502.c
+++ b/tests/libtest/lib2502.c
@@ -77,7 +77,7 @@ CURLcode test(char *URL)
     /* go http2 */
     easy_setopt(curl[i], CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_3ONLY);
     easy_setopt(curl[i], CURLOPT_CONNECTTIMEOUT_MS, (long)5000);
-    easy_setopt(curl[i], CURLOPT_CAINFO, "./certs/EdelCurlRoot-ca.cacert");
+    easy_setopt(curl[i], CURLOPT_CAINFO, libtest_arg4);
     /* wait for first connection established to see if we can share it */
     easy_setopt(curl[i], CURLOPT_PIPEWAIT, 1L);
     /* go verbose */
diff --git a/tests/libtest/test.h b/tests/libtest/test.h
index fad154da0b..d1dda0622f 100644
--- a/tests/libtest/test.h
+++ b/tests/libtest/test.h
@@ -65,6 +65,7 @@
 
 extern char *libtest_arg2; /* set by first.c to the argv[2] or NULL */
 extern char *libtest_arg3; /* set by first.c to the argv[3] or NULL */
+extern char *libtest_arg4; /* set by first.c to the argv[4] or NULL */
 
 /* argc and argv as passed in to the main() function */
 extern int test_argc;