diff --git a/src/util/virutil.c b/src/util/virutil.c
index 177f9d75fb1d79efcc183caa9d8b3fe07d93ad63..bb9604a0c1ffb9c99e454e84878a8c376f773046 100644
--- a/src/util/virutil.c
+++ b/src/util/virutil.c
@@ -2658,6 +2658,8 @@ virMemoryLimitIsSet(unsigned long long value)
  * @capped: whether the value must fit into unsigned long
  *   (long long is assumed otherwise)
  *
+ * Note: This function is mocked in tests/qemuxml2argvmock.c for test stability
+ *
  * Returns the maximum possible memory value in bytes.
  */
 unsigned long long
diff --git a/tests/qemuxml2argvmock.c b/tests/qemuxml2argvmock.c
index e58b8ce8b565825a4b9d767823ca3b04a2a49c42..8426108b29ed2dd59cb84743cd968ee2e6cac8d5 100644
--- a/tests/qemuxml2argvmock.c
+++ b/tests/qemuxml2argvmock.c
@@ -74,3 +74,13 @@ virTPMCreateCancelPath(const char *devpath)
 
     return path;
 }
+
+/**
+ * Large values for memory would fail on 32 bit systems, despite having
+ * variables that support it.
+ */
+unsigned long long
+virMemoryMaxValue(bool capped ATTRIBUTE_UNUSED)
+{
+    return LLONG_MAX;
+}