diff --git a/src/include/ngspice/cktdefs.h b/src/include/ngspice/cktdefs.h
index 48b021db4..ed52166b2 100644
--- a/src/include/ngspice/cktdefs.h
+++ b/src/include/ngspice/cktdefs.h
@@ -152,6 +152,7 @@ struct CKTcircuit {
 
     CKTnode *CKTnodes;          /* ??? */
     CKTnode *CKTlastNode;       /* ??? */
+    CKTnode *prev_CKTlastNode;  /* just before model setup */
 
     /* This define should be somewhere else ??? */
 #define NODENAME(ckt,nodenum) CKTnodName(ckt,nodenum)
diff --git a/src/spicelib/analysis/cktdltn.c b/src/spicelib/analysis/cktdltn.c
index 69f0c988b..deca3b294 100644
--- a/src/spicelib/analysis/cktdltn.c
+++ b/src/spicelib/analysis/cktdltn.c
@@ -23,6 +23,11 @@ CKTdltNNum(CKTcircuit *ckt, int num)
     CKTnode *n, *prev, *node, *sprev;
     int	error;
 
+    if (!ckt->prev_CKTlastNode->number || num <= ckt->prev_CKTlastNode->number) {
+        fprintf(stderr, "Internal Error: CKTdltNNum() removing a non device-local node, this will cause serious problems, please report this issue !\n");
+        controlled_exit(EXIT_FAILURE);
+    }
+
     prev  = NULL;
     node  = NULL;
     sprev = NULL;
diff --git a/src/spicelib/analysis/cktsens.c b/src/spicelib/analysis/cktsens.c
index 49adb07ce..e55c20d3b 100644
--- a/src/spicelib/analysis/cktsens.c
+++ b/src/spicelib/analysis/cktsens.c
@@ -364,10 +364,15 @@ int sens_sens(CKTcircuit *ckt, int restart)
 			ckt->CKTnumStates = sg->istate;
 
 			fn = DEVices[sg->dev]->DEVsetup;
-			if (fn)
-				fn (delta_Y, sg->model, ckt,
-					/* XXXX insert old state base here ?? */
-					&ckt->CKTnumStates);
+			if (fn) {
+                            CKTnode *n = ckt->CKTlastNode;
+                            /* XXXX insert old state base here ?? */
+                            fn (delta_Y, sg->model, ckt, &ckt->CKTnumStates);
+                            if (n != ckt->CKTlastNode) {
+                                fprintf(stderr, "Internal Error: node allocation in DEVsetup() during sensitivity analysis, this will cause serious troubles !, please report this issue !\n");
+                                controlled_exit(EXIT_FAILURE);
+                            }
+                        }
 
 			/* ? CKTsetup would call NIreinit instead */
 			ckt->CKTniState = NISHOULDREORDER | NIACSHOULDREORDER;
diff --git a/src/spicelib/analysis/cktsetup.c b/src/spicelib/analysis/cktsetup.c
index 220c24632..8804f24c4 100644
--- a/src/spicelib/analysis/cktsetup.c
+++ b/src/spicelib/analysis/cktsetup.c
@@ -77,6 +77,13 @@ CKTsetup(CKTcircuit *ckt)
     SetAnalyse("Device Setup", 0);
 #endif
 
+    /* preserve CKTlastNode before invoking DEVsetup()
+     * so we can check for incomplete CKTdltNNum() invocations
+     * during DEVunsetup() causing an erronous circuit matrix
+     *   when reinvoking CKTsetup()
+     */
+    ckt->prev_CKTlastNode = ckt->CKTlastNode;
+
     for (i=0;i<DEVmaxnum;i++) {
         if ( DEVices[i] && DEVices[i]->DEVsetup && ckt->CKThead[i] ) {
             error = DEVices[i]->DEVsetup (matrix, ckt->CKThead[i], ckt,
@@ -163,6 +170,13 @@ CKTunsetup(CKTcircuit *ckt)
                 error = e2;
         }
     }
+
+    if (ckt->prev_CKTlastNode != ckt->CKTlastNode) {
+        fprintf(stderr, "Internal Error: incomplete CKTunsetup(), this will cause serious problems, please report this issue !\n");
+        controlled_exit(EXIT_FAILURE);
+    }
+    ckt->prev_CKTlastNode = NULL;
+
     ckt->CKTisSetup = 0;
     if(error) return(error);