diff --git a/src/spicelib/devices/bjt/bjt.c b/src/spicelib/devices/bjt/bjt.c
index 69e5bd36a..655e88361 100644
--- a/src/spicelib/devices/bjt/bjt.c
+++ b/src/spicelib/devices/bjt/bjt.c
@@ -204,7 +204,8 @@ IFparm BJTmPTable[] = { /* model parameters */
  IOP("tmjs1",BJT_MOD_TMJS1, IF_REAL, "MJS 1. temperature coefficient"),
  IOP("tmjs2",BJT_MOD_TMJS2, IF_REAL, "MJS 2. temperature coefficient"),
  IOP("tns1", BJT_MOD_TNS1, IF_REAL, "NS 1. temperature coefficient"),
- IOP("tns2", BJT_MOD_TNS2, IF_REAL, "NS 2. temperature coefficient")
+ IOP("tns2", BJT_MOD_TNS2, IF_REAL, "NS 2. temperature coefficient"),
+ IOP("nkf", BJT_MOD_NKF, IF_REAL, "NKF High current beta rolloff exponent")
 };
 
 char *BJTnames[] = {
diff --git a/src/spicelib/devices/bjt/bjtdefs.h b/src/spicelib/devices/bjt/bjtdefs.h
index fade6dc6f..6c51ec0b8 100644
--- a/src/spicelib/devices/bjt/bjtdefs.h
+++ b/src/spicelib/devices/bjt/bjtdefs.h
@@ -430,6 +430,7 @@ typedef struct sBJTmodel {          /* model structure for a bjt */
     double BJTtmjs2;
     double BJTtns1;
     double BJTtns2;
+    double BJTnkf;
     double BJTinvEarlyVoltF;    /* inverse of BJTearlyVoltF */
     double BJTinvEarlyVoltR;    /* inverse of BJTearlyVoltR */
     double BJTinvRollOffF;  /* inverse of BJTrollOffF */
@@ -541,6 +542,7 @@ typedef struct sBJTmodel {          /* model structure for a bjt */
     unsigned BJTtmjs2Given : 1;
     unsigned BJTtns1Given : 1;
     unsigned BJTtns2Given : 1;
+    unsigned BJTnkfGiven : 1;
 } BJTmodel;
 
 #ifndef NPN
@@ -671,6 +673,7 @@ typedef struct sBJTmodel {          /* model structure for a bjt */
 #define BJT_MOD_TNS1 198
 #define BJT_MOD_TNS2 199
 #define BJT_MOD_SUBS 200
+#define BJT_MOD_NKF 100
 
 /* device questions */
 #define BJT_QUEST_FT             201
diff --git a/src/spicelib/devices/bjt/bjtload.c b/src/spicelib/devices/bjt/bjtload.c
index f1ef9439b..92bf6f88b 100644
--- a/src/spicelib/devices/bjt/bjtload.c
+++ b/src/spicelib/devices/bjt/bjtload.c
@@ -478,10 +478,19 @@ next1:      vtn=vt*here->BJTtemissionCoeffF;
                 q2=oik*cbe+oikr*cbc;
                 arg=MAX(0,1+4*q2);
                 sqarg=1;
-                if(arg != 0) sqarg=sqrt(arg);
+                if(!model->BJTnkfGiven) {
+                    if(arg != 0) sqarg=sqrt(arg);
+                } else {
+                    if(arg != 0) sqarg=pow(arg,model->BJTnkf);
+                }
                 qb=q1*(1+sqarg)/2;
-                dqbdve=q1*(qb*here->BJTtinvEarlyVoltR+oik*gbe/sqarg);
-                dqbdvc=q1*(qb*here->BJTtinvEarlyVoltF+oikr*gbc/sqarg);
+                if(!model->BJTnkfGiven) {
+                    dqbdve=q1*(qb*here->BJTtinvEarlyVoltR+oik*gbe/sqarg);
+                    dqbdvc=q1*(qb*here->BJTtinvEarlyVoltF+oikr*gbc/sqarg);
+                } else {
+                    dqbdve=q1*(qb*here->BJTtinvEarlyVoltR+oik*gbe*2*sqarg*model->BJTnkf/arg);
+                    dqbdvc=q1*(qb*here->BJTtinvEarlyVoltF+oikr*gbc*2*sqarg*model->BJTnkf/arg);
+                }
             }
             /*
              *   weil's approx. for excess phase applied with backward-
diff --git a/src/spicelib/devices/bjt/bjtmask.c b/src/spicelib/devices/bjt/bjtmask.c
index 440e0edfd..85ae27e99 100644
--- a/src/spicelib/devices/bjt/bjtmask.c
+++ b/src/spicelib/devices/bjt/bjtmask.c
@@ -357,6 +357,9 @@ BJTmAsk(CKTcircuit *ckt, GENmodel *instPtr, int which, IFvalue *value)
         case BJT_MOD_TNS2:
             value->rValue = here->BJTtns2;
             return(OK);
+        case BJT_MOD_NKF:
+            value->rValue = here->BJTnkf;
+            return(OK);
         default:
             return(E_BADPARM);
     }
diff --git a/src/spicelib/devices/bjt/bjtmpar.c b/src/spicelib/devices/bjt/bjtmpar.c
index bed92d9ee..f2e1799a8 100644
--- a/src/spicelib/devices/bjt/bjtmpar.c
+++ b/src/spicelib/devices/bjt/bjtmpar.c
@@ -426,6 +426,10 @@ BJTmParam(int param, IFvalue *value, GENmodel *inModel)
             mods->BJTtns2 = value->rValue;
             mods->BJTtns2Given = TRUE;
             break;
+        case BJT_MOD_NKF:
+            mods->BJTnkf = value->rValue;
+            mods->BJTnkfGiven = TRUE;
+            break;
         default:
             return(E_BADPARM);
     }
diff --git a/src/spicelib/devices/bjt/bjtsetup.c b/src/spicelib/devices/bjt/bjtsetup.c
index 35b3d42fd..3aee05f31 100644
--- a/src/spicelib/devices/bjt/bjtsetup.c
+++ b/src/spicelib/devices/bjt/bjtsetup.c
@@ -296,6 +296,14 @@ BJTsetup(SMPmatrix *matrix, GENmodel *inModel, CKTcircuit *ckt, int *states)
         if(!model->BJTtns2Given) {
             model->BJTtns2 = 0.0;
         }
+        if(!model->BJTnkfGiven) {
+            model->BJTnkf = 0.5;
+        } else {
+          if (model->BJTnkf > 1.0) {
+            printf("Warning: NKF has been set to its maximum value: 1.0\n");
+            model->BJTnkf = 1.0;
+          } 
+        }
 
 /*
  * COMPATABILITY WARNING!