diff --git a/src/spicelib/devices/dio/diotemp.c b/src/spicelib/devices/dio/diotemp.c
index 10b6b370d..8853d70ec 100644
--- a/src/spicelib/devices/dio/diotemp.c
+++ b/src/spicelib/devices/dio/diotemp.c
@@ -38,6 +38,13 @@ DIOtemp(GENmodel *inModel, CKTcircuit *ckt)
             model->DIOnomTemp = ckt->CKTnomTemp;
         }
         vtnom = CONSTKoverQ * model->DIOnomTemp;
+        /* limit grading coeff to max of .9 */
+        if(model->DIOgradingCoeff>.9) {
+            SPfrontEnd->IFerrorf (ERR_WARNING,
+                    "%s: grading coefficient too large, limited to 0.9",
+                    model->DIOmodName);
+            model->DIOgradingCoeff=.9;
+        }
         /* limit activation energy to min of .1 */
         if(model->DIOactivationEnergy<.1) {
             SPfrontEnd->IFerrorf (ERR_WARNING,
@@ -87,6 +94,16 @@ DIOtemp(GENmodel *inModel, CKTcircuit *ckt)
                          + (model->DIOgradCoeffTemp2 * dt * dt);
             here->DIOtGradingCoeff = model->DIOgradingCoeff * factor;
 
+            /* limit temperature adjusted grading coeff
+             * to max of .9
+             */
+            if(here->DIOtGradingCoeff>.9) {
+              SPfrontEnd->IFerrorf (ERR_WARNING,
+                    "%s: temperature adjusted grading coefficient too large, limited to 0.9",
+                    here->DIOname);
+              here->DIOtGradingCoeff=.9;
+            }
+
             vt = CONSTKoverQ * here->DIOtemp;
             /* this part gets really ugly - I won't even try to
              * explain these equations */