diff --git a/run-tests.php b/run-tests.php
index 8e6f7f519fb9d..805e2ccaa5603 100755
--- a/run-tests.php
+++ b/run-tests.php
@@ -1260,6 +1260,13 @@ function system_with_timeout(
 ) {
     global $valgrind;
 
+    // when proc_open cmd is passed as a string (without bypass_shell=true option) the cmd goes thru shell
+    // and on Windows quotes are discarded, this is a fix to honor the quotes and allow values containing
+    // spaces like '"C:\Program Files\PHP\php.exe"' to be passed as 1 argument correctly
+    if (IS_WINDOWS) {
+        $commandline = 'start "" /b /wait ' . $commandline;
+    }
+
     $data = '';
 
     $bin_env = [];