diff --git a/tests/unit/CMakeLists.txt b/tests/unit/CMakeLists.txt
index bd8de62cb1..6096660b0f 100644
--- a/tests/unit/CMakeLists.txt
+++ b/tests/unit/CMakeLists.txt
@@ -569,7 +569,7 @@ function(seastar_add_certgen name)
     WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}
   )
   add_custom_command(OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/${CERT_CAROOT}"
-    COMMAND ${OPENSSL} req -x509 -new -nodes -key ${CERT_CAPRIVKEY} -days ${CERT_DAYS} -config ${CERT_NAME}.cfg -out ${CERT_CAROOT}
+    COMMAND ${OPENSSL} req -x509 -new -nodes -key ${CERT_CAPRIVKEY} -days ${CERT_DAYS} -config ${CERT_NAME}.cfg -out ${CERT_CAROOT} -extensions v3_ca
     DEPENDS "${CMAKE_CURRENT_BINARY_DIR}/${CERT_CAPRIVKEY}" "${CMAKE_CURRENT_BINARY_DIR}/${CERT_NAME}.cfg"
     WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}
   )