diff --git a/src/include/ngspice/pssdefs.h b/src/include/ngspice/pssdefs.h
index 45dce527c..340dbee5e 100644
--- a/src/include/ngspice/pssdefs.h
+++ b/src/include/ngspice/pssdefs.h
@@ -50,6 +50,7 @@ typedef struct {
     double PACfStop;         /* input-frequency sweep stop (Hz) */
     int    PACpoints;        /* points per decade/octave, or total for linear */
     int    PACstepType;      /* 0 = LIN, 1 = DEC, 2 = OCT */
+    int    PACmaxSideband;   /* number of output conversion sidebands each side (0 = sb0 only) */
 } PSSan;
 
 enum {
@@ -66,6 +67,7 @@ enum {
     PAC_FSTOP,
     PAC_POINTS,
     PAC_STEPTYPE,
+    PAC_MAXSB,
 };
 
 #endif
diff --git a/src/maths/KLU/klusmp.c b/src/maths/KLU/klusmp.c
index 1546fd3a7..e82010d40 100644
--- a/src/maths/KLU/klusmp.c
+++ b/src/maths/KLU/klusmp.c
@@ -1852,6 +1852,10 @@ SMPfindElt (SMPmatrix *eMatrix, int Row, int Col, int CreateIfMissing)
         assert (IS_SPARSE (Matrix)) ;
         Row = Matrix->ExtToIntRowMap [Row] ;
         Col = Matrix->ExtToIntColMap [Col] ;
+        if (Row < 0 || Col < 0) {
+            fprintf(stderr, "Warning: element not found, as internal Row/Col map is not avaialable!\n");
+            return NULL;
+        }
         Element = Matrix->FirstInCol [Col] ;
         Element = spcFindElementInCol (Matrix, &Element, Row, Col, CreateIfMissing) ;
         return (SMPelement *)Element ;