diff --git a/coregrind/m_syswrap/syswrap-linux.c b/coregrind/m_syswrap/syswrap-linux.c
index 8d2f7d880..4136f59b4 100644
--- a/coregrind/m_syswrap/syswrap-linux.c
+++ b/coregrind/m_syswrap/syswrap-linux.c
@@ -9013,10 +9013,10 @@ PRE(sys_ioctl)
 
 POST(sys_ioctl)
 {
-   vg_assert(SUCCESS || (FAILURE && VKI_DRM_IOCTL_VERSION == ARG2));
-
    ARG2 = (UInt)ARG2;
 
+   vg_assert(SUCCESS || (FAILURE && VKI_DRM_IOCTL_VERSION == ARG2));
+
    /* --- BEGIN special IOCTL handlers for specific Android hardware --- */
 
    /* BEGIN undocumented ioctls for PowerVR SGX 540 (the GPU on Nexus S) */