diff --git a/vpi_user.h b/vpi_user.h
index d851b57d6..fa2eac5db 100644
--- a/vpi_user.h
+++ b/vpi_user.h
@@ -351,14 +351,8 @@ typedef struct t_vpi_delay  {
 #define vpiAutomatic      50
 #define vpiConstantSelect 53
 #define vpiSigned         65
-/* IVL private properties */
+/* IVL private properties, also see vvp/vpi_priv.h for other properties */
 #define _vpiNexusId 0x1000000
-#define _vpiFromThr 0x1000001
-#   define _vpiNoThr  0
-#   define _vpiVThr   1
-#   define _vpiWord   2
-#   define _vpi_at_PV 3
-#   define _vpi_at_A  4
 
 /* DELAY MODES */
 #define vpiNoDelay            1
diff --git a/vvp/vpi_priv.h b/vvp/vpi_priv.h
index 9870811e0..d9f599107 100644
--- a/vvp/vpi_priv.h
+++ b/vvp/vpi_priv.h
@@ -37,6 +37,18 @@
  * header file elsewhere.
  */
 
+/*
+ * Private VPI properties that are only used in the cleanup code.
+ */
+#ifdef CHECK_WITH_VALGRIND
+#define _vpiFromThr 0x1000001
+#   define _vpiNoThr  0
+#   define _vpiVThr   1
+#   define _vpiWord   2
+#   define _vpi_at_PV 3
+#   define _vpi_at_A  4
+#endif
+
 
 /*
  * The vpi_mode_flag contains the major mode for VPI use. This is used