diff --git a/src/frontend/inp.c b/src/frontend/inp.c
index c12489ef8..a4c260df1 100644
--- a/src/frontend/inp.c
+++ b/src/frontend/inp.c
@@ -963,6 +963,10 @@ inp_spsource(FILE *fp, bool comfile, char *filename, bool intfile)
             /* Translate all SPICE 2G6 polynomial type sources */
             deck->nextcard = ENHtranslate_poly(deck->nextcard);
 #endif
+            /* quote nodes of degmons, is required for  parsing the a device node,
+               when [x] is part of a node nname. */
+            int err = 0;
+            err = quote_degmons(deck->nextcard);
 
             line_free(deck->actualLine, FALSE);
             deck->actualLine = realdeck;
diff --git a/src/frontend/inpcom.c b/src/frontend/inpcom.c
index 124e637ec..8d6a8b260 100644
--- a/src/frontend/inpcom.c
+++ b/src/frontend/inpcom.c
@@ -1100,6 +1100,9 @@ struct card *inp_readall(FILE *fp, const char *dir_name, const char* file_name,
         /* collect .agemodel data */
         readdegparams(working);
 
+        /* Add degradation monitors to devices in X lines */
+        adddegmonitors(working);
+
         if (newcompat.lt && newcompat.a)
             ltspice_compat_a(working);
         if (newcompat.ps && newcompat.a)
diff --git a/src/frontend/inpcom.h b/src/frontend/inpcom.h
index 18fd33a48..502ec8379 100644
--- a/src/frontend/inpcom.h
+++ b/src/frontend/inpcom.h
@@ -14,5 +14,7 @@ extern char* inp_remove_ws(char* s);
 extern char* search_plain_identifier(char* str, const char* identifier);
 
 extern int readdegparams(struct card* deck);
+extern int adddegmonitors(struct card* deck);
+extern int quote_degmons(struct card* deck);
 
 #endif
diff --git a/src/frontend/inpdeg.c b/src/frontend/inpdeg.c
index 1ee7d0bd2..9ca563c2e 100644
--- a/src/frontend/inpdeg.c
+++ b/src/frontend/inpdeg.c
@@ -91,6 +91,10 @@ int readdegparams (struct card *deck) {
                 ftok = dftok = gettok(&cut_line);
                 /* parameter name */
                 f1 = gettok_char(&ftok, '=', FALSE, FALSE);
+                if (!f1) {
+                    fprintf(stderr, "Error: bad.agemodel syntax in line\n % s", card->line);
+                    controlled_exit(1);
+                }
                 /* parameter value */
                 f2 = copy(ftok + 1);
                 agemods[ageindex].paramnames[parno] = f1;
@@ -116,4 +120,148 @@ int readdegparams (struct card *deck) {
     return 0;
 }
 
+/* Look for an X line.
+   Check if the model in the x line is found in the model list agemodds.
+   Create a degradation monitor for each x line if model found.
+   Add the x instance name to the degmod name.
+   Add degmon line and its model line to the netlist.*/
+int adddegmonitors(struct card* deck) {
+    static int degmonno;
+    double tfuture = 315336e4;
+    int nodes = 4;
+    if (agemods[0].paramhash == NULL)
+        return 1;
+    for (; deck; deck = deck->nextcard) {
+        int skip_control = 0;
 
+        char* line = deck->line;
+
+        if (*line == '*') {
+            continue;
+        }
+        /* there is no e source inside .control ... .endc */
+        if (ciprefix(".control", line)) {
+            skip_control++;
+            continue;
+        }
+        else if (ciprefix(".endc", line)) {
+            skip_control--;
+            continue;
+        }
+        else if (skip_control > 0) {
+            continue;
+        }
+        if (*line == 'x') {
+            char *modname, *fournodes, *instname;
+            int ii;
+//            fprintf(stdout, "%.80s\n", line);
+            /* x  instance model in subcircuit */
+            /* get instance name */
+            instname = gettok_instance(&line);
+            fournodes = line;
+            /* and 4 nodes */
+            for (ii = 0; ii < nodes; ii++)
+                line = nexttok(line);
+            if (!line) {
+                /* Must be something else, not a 4-node MOS */
+                continue;
+            }
+            fournodes = copy_substring(fournodes, line);
+            modname = gettok(&line);
+
+            /*check if model is available in agemods */
+            for (ii = 0; ii < DEGMODMAX; ii++) {
+                if (agemods[ii].devmodel) {
+                    if (cieq(modname, agemods[ii].devmodel)) {
+//                        fprintf(stdout, "device model %s found as no. %d\n\n", modname, ii);
+                        /* get the channel length */
+                        char* lpos = strstr(line, "l=");
+                        if (!lpos) {
+                             fprintf(stderr, "Error, l not found in device %s \n\n", deck->line);
+                             return 1;
+                        }
+                        char* clength = gettok(&lpos);
+                        /* Now add a degradation monitor like
+                           adegmon1 %v([z a vss vss]) mon degmon1
+                          .model degmon1 degmon (tfuture=3153360000 l=0.15e-6 devmod="sg13_lv_nmos")
+                         */
+                        char* aline = tprintf("adegmon%d_%s %%v([%s]) mon%d degmon%d\n", 
+                            degmonno, instname, fournodes, degmonno, degmonno);
+                        char* mline = tprintf(".model degmon%d degmon (tfuture=%e %s devmod=\"%s\"\n",
+                            degmonno, tfuture, clength, modname);
+                        tfree(clength);
+                        insert_new_line(deck, aline, 0, deck->linenum_orig, deck->linesource);
+                        insert_new_line(deck, mline, 0, deck->linenum_orig, deck->linesource);
+                        degmonno++;
+                        break;
+                    }
+                }
+                else {
+//                    fprintf(stderr, "No model found for device %.80s \n\n", deck->line);
+                    break;
+                }
+            }
+            tfree(fournodes);
+            tfree(modname);
+            tfree(instname);
+        }
+    }
+    return 0;
+}
+
+int quote_degmons(struct card* deck) {
+    for (; deck; deck = deck->nextcard) {
+        int skip_control = 0;
+
+        char* line = deck->line;
+
+        if (*line == '*') {
+            continue;
+        }
+        /* there is no e source inside .control ... .endc */
+        if (ciprefix(".control", line)) {
+            skip_control++;
+            continue;
+        }
+        else if (ciprefix(".endc", line)) {
+            skip_control--;
+            continue;
+        }
+        else if (skip_control > 0) {
+            continue;
+        }
+        if (*line == 'a' && strstr(line, "adegmon")) {
+            char allnodes[1024];
+            allnodes[0] = '\0';
+            int ii, nodes = 4;
+            char* newnodes, *instname;
+            instname = gettok_instance(&line);
+            /* skip %v */
+            line = nexttok(line);
+            char* deltoken;
+            char* nodetoken = deltoken = gettok_char(&line, ']', false, true);
+            if (!nodetoken)
+                break;
+            /* go beyond '[' */
+            nodetoken++;
+            for (ii = 0; ii < nodes; ii++) {
+                char* nexttoken = gettok(&nodetoken);
+                sprintf(allnodes, "%s \"%s\"", allnodes, nexttoken);
+                if (!nexttoken)
+                    break;
+                tfree(nexttoken);
+            }
+            if (!line || eq(line, "")) {
+                /* Must be something else, not a 4-node MOS */
+                continue;
+            }
+            newnodes = tprintf("%s %%v [ %s %s", instname, allnodes, line);
+
+            tfree(deltoken);
+            tfree(instname);
+            tfree(deck->line);
+            deck->line = newnodes;
+        }
+    }
+    return 0;
+}