diff --git a/src/ciderlib/oned/oneadmit.c b/src/ciderlib/oned/oneadmit.c
index bdf097004..9920a2f55 100644
--- a/src/ciderlib/oned/oneadmit.c
+++ b/src/ciderlib/oned/oneadmit.c
@@ -91,10 +91,10 @@ NUMDadmittance(ONEdevice *pDevice, double omega, SPcomplex *yd)
     if (SORFailed && AcAnalysisMethod == SOR) {
       AcAnalysisMethod = DIRECT;
       printf("SOR failed at %g Hz, switching to direct-method ac analysis.\n",
-	  omega / (TWO_PI * TNorm) );
+	  omega / (2 * M_PI * TNorm) );
     } else if (SORFailed) {	/* Told to only do SOR, so give up. */
       printf("SOR failed at %g Hz, returning null admittance.\n",
-	  omega / (TWO_PI * TNorm) );
+	  omega / (2 * M_PI * TNorm) );
       CMPLX_ASSIGN_VALUE(*yd, 0.0, 0.0);
       return (AcAnalysisMethod);
     }
@@ -215,10 +215,10 @@ NBJTadmittance(ONEdevice *pDevice, double omega, SPcomplex *yIeVce,
     if (SORFailed && (AcAnalysisMethod == SOR)) {
       AcAnalysisMethod = DIRECT;
       printf("SOR failed at %g Hz, switching to direct-method ac analysis.\n",
-	  omega / (TWO_PI * TNorm) );
+	  omega / (2 * M_PI * TNorm) );
     } else if (SORFailed) {	/* Told to only do SOR, so give up. */
       printf("SOR failed at %g Hz, returning null admittance.\n",
-	  omega / (TWO_PI * TNorm) );
+	  omega / (2 * M_PI * TNorm) );
       CMPLX_ASSIGN_VALUE(*yIeVce, 0.0, 0.0);
       CMPLX_ASSIGN_VALUE(*yIcVce, 0.0, 0.0);
       CMPLX_ASSIGN_VALUE(*yIeVbe, 0.0, 0.0);
@@ -260,10 +260,10 @@ NBJTadmittance(ONEdevice *pDevice, double omega, SPcomplex *yIeVce,
       if (SORFailed && (AcAnalysisMethod == SOR)) {
 	AcAnalysisMethod = DIRECT;
 	printf("SOR failed at %g Hz, switching to direct-method ac analysis.\n",
-	    omega / (TWO_PI * TNorm) );
+	    omega / (2 * M_PI * TNorm) );
       } else if (SORFailed) {	/* Told to only do SOR, so give up. */
 	printf("SOR failed at %g Hz, returning null admittance.\n",
-	    omega / (TWO_PI * TNorm) );
+	    omega / (2 * M_PI * TNorm) );
 	CMPLX_ASSIGN_VALUE(*yIeVce, 0.0, 0.0);
 	CMPLX_ASSIGN_VALUE(*yIcVce, 0.0, 0.0);
 	CMPLX_ASSIGN_VALUE(*yIeVbe, 0.0, 0.0);
diff --git a/src/ciderlib/twod/twoadmit.c b/src/ciderlib/twod/twoadmit.c
index 14806dea3..bf877639c 100644
--- a/src/ciderlib/twod/twoadmit.c
+++ b/src/ciderlib/twod/twoadmit.c
@@ -78,10 +78,10 @@ NUMD2admittance(TWOdevice *pDevice, double omega, SPcomplex *yd)
     if (SORFailed && AcAnalysisMethod == SOR) {
       AcAnalysisMethod = DIRECT;
       printf("SOR failed at %g Hz, switching to direct-method ac analysis.\n",
-	  omega / (TWO_PI * TNorm) );
+	  omega / (2 * M_PI * TNorm) );
     } else if (SORFailed) {	/* Told to only do SOR, so give up. */
       printf("SOR failed at %g Hz, returning null admittance.\n",
-	  omega / (TWO_PI * TNorm) );
+	  omega / (2 * M_PI * TNorm) );
       CMPLX_ASSIGN_VALUE(*yd, 0.0, 0.0);
       return (AcAnalysisMethod);
     }
@@ -199,10 +199,10 @@ NBJT2admittance(TWOdevice *pDevice, double omega, SPcomplex *yIeVce,
     if (SORFailed && AcAnalysisMethod == SOR) {
       AcAnalysisMethod = DIRECT;
       printf("SOR failed at %g Hz, switching to direct-method ac analysis.\n",
-	  omega / (TWO_PI * TNorm) );
+	  omega / (2 * M_PI * TNorm) );
     } else if (SORFailed) {	/* Told to only do SOR, so give up. */
       printf("SOR failed at %g Hz, returning null admittance.\n",
-	  omega / (TWO_PI * TNorm) );
+	  omega / (2 * M_PI * TNorm) );
       CMPLX_ASSIGN_VALUE(*yIeVce, 0.0, 0.0);
       CMPLX_ASSIGN_VALUE(*yIcVce, 0.0, 0.0);
       CMPLX_ASSIGN_VALUE(*yIeVbe, 0.0, 0.0);
@@ -236,10 +236,10 @@ NBJT2admittance(TWOdevice *pDevice, double omega, SPcomplex *yIeVce,
       if (SORFailed && AcAnalysisMethod == SOR) {
 	AcAnalysisMethod = DIRECT;
 	printf("SOR failed at %g Hz, switching to direct-method ac analysis.\n",
-	    omega / (TWO_PI * TNorm) );
+	    omega / (2 * M_PI * TNorm) );
       } else if (SORFailed) {	/* Told to only do SOR, so give up. */
 	printf("SOR failed at %g Hz, returning null admittance.\n",
-	    omega / (TWO_PI * TNorm) );
+	    omega / (2 * M_PI * TNorm) );
 	CMPLX_ASSIGN_VALUE(*yIeVce, 0.0, 0.0);
 	CMPLX_ASSIGN_VALUE(*yIcVce, 0.0, 0.0);
 	CMPLX_ASSIGN_VALUE(*yIeVbe, 0.0, 0.0);
@@ -390,10 +390,10 @@ NUMOSadmittance(TWOdevice *pDevice, double omega, struct mosAdmittances *yAc)
     if (SORFailed && AcAnalysisMethod == SOR) {
       AcAnalysisMethod = DIRECT;
       printf("SOR failed at %g Hz, switching to direct-method ac analysis.\n",
-	  omega / (TWO_PI * TNorm) );
+	  omega / (2 * M_PI * TNorm) );
     } else if (SORFailed) {	/* Told to only do SOR, so give up. */
       printf("SOR failed at %g Hz, returning null admittance.\n",
-	  omega / (TWO_PI * TNorm) );
+	  omega / (2 * M_PI * TNorm) );
       CMPLX_ASSIGN_VALUE(yAc->yIdVdb, 0.0, 0.0);
       CMPLX_ASSIGN_VALUE(yAc->yIdVsb, 0.0, 0.0);
       CMPLX_ASSIGN_VALUE(yAc->yIdVgb, 0.0, 0.0);
@@ -435,10 +435,10 @@ NUMOSadmittance(TWOdevice *pDevice, double omega, struct mosAdmittances *yAc)
       if (SORFailed && AcAnalysisMethod == SOR) {
 	AcAnalysisMethod = DIRECT;
 	printf("SOR failed at %g Hz, switching to direct-method ac analysis.\n",
-	    omega / (TWO_PI * TNorm) );
+	    omega / (2 * M_PI * TNorm) );
       } else if (SORFailed) {	/* Told to only do SOR, so give up. */
 	printf("SOR failed at %g Hz, returning null admittance.\n",
-	    omega / (TWO_PI * TNorm) );
+	    omega / (2 * M_PI * TNorm) );
 	CMPLX_ASSIGN_VALUE(yAc->yIdVdb, 0.0, 0.0);
 	CMPLX_ASSIGN_VALUE(yAc->yIdVsb, 0.0, 0.0);
 	CMPLX_ASSIGN_VALUE(yAc->yIdVgb, 0.0, 0.0);
@@ -482,10 +482,10 @@ NUMOSadmittance(TWOdevice *pDevice, double omega, struct mosAdmittances *yAc)
 	if (SORFailed && AcAnalysisMethod == SOR) {
 	  AcAnalysisMethod = DIRECT;
 	  printf("SOR failed at %g Hz, switching to direct-method ac analysis.\n",
-	      omega / (TWO_PI * TNorm) );
+	      omega / (2 * M_PI * TNorm) );
 	} else if (SORFailed) {	/* Told to only do SOR, so give up. */
 	  printf("SOR failed at %g Hz, returning null admittance.\n",
-	      omega / (TWO_PI * TNorm) );
+	      omega / (2 * M_PI * TNorm) );
 	  CMPLX_ASSIGN_VALUE(yAc->yIdVdb, 0.0, 0.0);
 	  CMPLX_ASSIGN_VALUE(yAc->yIdVsb, 0.0, 0.0);
 	  CMPLX_ASSIGN_VALUE(yAc->yIdVgb, 0.0, 0.0);
diff --git a/src/include/ngspice/numconst.h b/src/include/ngspice/numconst.h
index 1d860605a..0157cc697 100644
--- a/src/include/ngspice/numconst.h
+++ b/src/include/ngspice/numconst.h
@@ -13,13 +13,6 @@ Authors: 1987 Karti Mayaram, 1991 David Gates
 #ifndef ngspice_NUMCONST_H
 #define ngspice_NUMCONST_H
 
-/* Mathematical Constants */
-#ifdef PI
-#undef PI
-#endif
-#define  PI	        3.14159265358979323846264338327950288419716939937511
-#define  TWO_PI		(2.0 * PI)
-#define  ROOT_TWO	1.41421356237309504880168872420969807856967187537694
 
 /* Basic Physical Constants */
 #ifdef CHARGE