diff --git a/src/maths/ni/niiter.c b/src/maths/ni/niiter.c
index e7c115836..332926031 100644
--- a/src/maths/ni/niiter.c
+++ b/src/maths/ni/niiter.c
@@ -246,8 +246,9 @@ NIiter(CKTcircuit *ckt, int maxIter)
                CKTnumStates the first time it is run */
             if (!OldCKTstate0)
                 OldCKTstate0 = TMALLOC(double, ckt->CKTnumStates + 1);
-            memcpy(OldCKTstate0, ckt->CKTstate0,
-                   (size_t) ckt->CKTnumStates * sizeof(double));
+            if (ckt->CKTstate0)
+                memcpy(OldCKTstate0, ckt->CKTstate0,
+                       (size_t) ckt->CKTnumStates * sizeof(double));
 
             startTime = SPfrontEnd->IFseconds();
             SMPsolve(ckt->CKTmatrix, ckt->CKTrhs, ckt->CKTrhsSpare);
diff --git a/src/spicelib/analysis/dctran.c b/src/spicelib/analysis/dctran.c
index 3c02a6dba..9915e0836 100644
--- a/src/spicelib/analysis/dctran.c
+++ b/src/spicelib/analysis/dctran.c
@@ -341,8 +341,10 @@ DCtran(CKTcircuit *ckt,
         ckt->CKTmode = (ckt->CKTmode&MODEUIC) | MODETRAN | MODEINITTRAN;
         /* modeinittran set here */
         ckt->CKTag[0]=ckt->CKTag[1]=0;
-        memcpy(ckt->CKTstate1, ckt->CKTstate0,
-              (size_t) ckt->CKTnumStates * sizeof(double));
+        if (ckt->CKTstate1 && ckt->CKTstate0) {
+            memcpy(ckt->CKTstate1, ckt->CKTstate0,
+                  (size_t) ckt->CKTnumStates * sizeof(double));
+        }
 
 #ifdef WANT_SENSE2
         if(ckt->CKTsenInfo && (ckt->CKTsenInfo->SENmode & TRANSEN)){
@@ -790,7 +792,7 @@ resume:
 
         ckt->CKTstat->STATtimePts ++;
         ckt->CKTmode = (ckt->CKTmode&MODEUIC)|MODETRAN | MODEINITPRED;
-        if(firsttime) {
+        if(firsttime && ckt->CKTstate1 && ckt->CKTstate2 && ckt->CKTstate3) {
             memcpy(ckt->CKTstate2, ckt->CKTstate1,
                    (size_t) ckt->CKTnumStates * sizeof(double));
             memcpy(ckt->CKTstate3, ckt->CKTstate1,
diff --git a/src/spicelib/analysis/dctrcurv.c b/src/spicelib/analysis/dctrcurv.c
index 3ef5986d6..f2a46d3b4 100644
--- a/src/spicelib/analysis/dctrcurv.c
+++ b/src/spicelib/analysis/dctrcurv.c
@@ -456,8 +456,10 @@ DCtrCurv(CKTcircuit *ckt, int restart)
 
         if (firstTime) {
             firstTime = 0;
-            memcpy(ckt->CKTstate1, ckt->CKTstate0,
-                   (size_t) ckt->CKTnumStates * sizeof(double));
+            if (ckt->CKTstate1 && ckt->CKTstate0) {
+                memcpy(ckt->CKTstate1, ckt->CKTstate0,
+                       (size_t) ckt->CKTnumStates * sizeof(double));
+            }
         }
 
         i = 0;