diff --git a/src/include/ngspice/cktdefs.h b/src/include/ngspice/cktdefs.h
index f129016a9..451b4dc51 100644
--- a/src/include/ngspice/cktdefs.h
+++ b/src/include/ngspice/cktdefs.h
@@ -165,6 +165,9 @@ struct CKTcircuit {
 #define MODETRAN           0x1
 #define MODEAC             0x2
 
+/* for noise analysis */
+#define MODEACNOISE        0x8
+
 /* old 'modedc' parameters */
 #define MODEDC            0x70
 #define MODEDCOP          0x10
@@ -288,6 +291,8 @@ struct CKTcircuit {
 
     NGHASHPTR DEVnameHash;
     NGHASHPTR MODnameHash;
+
+    GENinstance *noise_input;   /* identify the input vsrc/isrc during noise analysis */
 };
 
 
diff --git a/src/spicelib/analysis/noisean.c b/src/spicelib/analysis/noisean.c
index 48345d9a3..340184b02 100644
--- a/src/spicelib/analysis/noisean.c
+++ b/src/spicelib/analysis/noisean.c
@@ -37,13 +37,13 @@ NOISEan (CKTcircuit *ckt, int restart)
     double freqTol; /* tolerence parameter for finding final frequency; hack */
 
     NOISEAN *job = (NOISEAN *) ckt->CKTcurJob;
+    GENinstance *inst = CKTfndDev(ckt, job->input);
 
     posOutNode = (job->output) -> number;
     negOutNode = (job->outputRef) -> number;
 
     /* see if the source specified is AC */
     {
-        GENinstance *inst = CKTfndDev(ckt, job->input);
         bool ac_given = FALSE;
 
         if (!inst || inst->GENmodPtr->GENmodType < 0) {
@@ -194,7 +194,8 @@ NOISEan (CKTcircuit *ckt, int restart)
 	    return (E_PAUSE);
         }
 	ckt->CKTomega = 2.0 * M_PI * data->freq;
-	ckt->CKTmode = (ckt->CKTmode & MODEUIC) | MODEAC;
+	ckt->CKTmode = (ckt->CKTmode & MODEUIC) | MODEAC | MODEACNOISE;
+	ckt->noise_input = inst;
 
 	/*
 	 * solve the original AC system to get the transfer
diff --git a/src/spicelib/devices/isrc/isrcacld.c b/src/spicelib/devices/isrc/isrcacld.c
index 5ddbec373..2a8cefff1 100644
--- a/src/spicelib/devices/isrc/isrcacld.c
+++ b/src/spicelib/devices/isrc/isrcacld.c
@@ -23,16 +23,26 @@ ISRCacLoad(GENmodel *inModel, CKTcircuit *ckt)
         for (here = model->ISRCinstances; here != NULL ;
                 here=here->ISRCnextInstance) {
 
+            double acReal, acImag;
+
+            if ((ckt->CKTmode & MODEACNOISE) && (here == ckt->noise_input)) {
+                acReal = 1.0;
+                acImag = 0.0;
+            } else {
+                acReal = here->ISRCacReal;
+                acImag = here->ISRCacImag;
+            }
+
             m = here->ISRCmValue;
 
             *(ckt->CKTrhs + (here->ISRCposNode)) +=
-                m * here->ISRCacReal;
+                m * acReal;
             *(ckt->CKTrhs + (here->ISRCnegNode)) -=
-                m * here->ISRCacReal;
+                m * acReal;
             *(ckt->CKTirhs + (here->ISRCposNode)) +=
-                m * here->ISRCacImag;
+                m * acImag;
             *(ckt->CKTirhs + (here->ISRCnegNode)) -=
-                m * here->ISRCacImag;
+                m * acImag;
         }
     }
 
diff --git a/src/spicelib/devices/vsrc/vsrcacld.c b/src/spicelib/devices/vsrc/vsrcacld.c
index 5b7b9058b..8229bb842 100644
--- a/src/spicelib/devices/vsrc/vsrcacld.c
+++ b/src/spicelib/devices/vsrc/vsrcacld.c
@@ -22,12 +22,22 @@ VSRCacLoad(GENmodel *inModel, CKTcircuit *ckt)
         for (here = model->VSRCinstances; here != NULL ;
                 here=here->VSRCnextInstance) {
 
+            double acReal, acImag;
+
+            if ((ckt->CKTmode & MODEACNOISE) && (here == ckt->noise_input)) {
+                acReal = 1.0;
+                acImag = 0.0;
+            } else {
+                acReal = here->VSRCacReal;
+                acImag = here->VSRCacImag;
+            }
+
             *(here->VSRCposIbrptr) += 1.0 ;
             *(here->VSRCnegIbrptr) -= 1.0 ;
             *(here->VSRCibrPosptr) += 1.0 ;
             *(here->VSRCibrNegptr) -= 1.0 ;
-            *(ckt->CKTrhs + (here->VSRCbranch)) += here->VSRCacReal;
-            *(ckt->CKTirhs + (here->VSRCbranch)) += here->VSRCacImag;
+            *(ckt->CKTrhs + (here->VSRCbranch)) += acReal;
+            *(ckt->CKTirhs + (here->VSRCbranch)) += acImag;
         }
     }