diff --git a/compile_linux.sh b/compile_linux.sh
index d70f9145f..9c8cb9c54 100755
--- a/compile_linux.sh
+++ b/compile_linux.sh
@@ -52,14 +52,14 @@ if test "$1" = "d"; then
   echo "configuring for 64 bit debug"
   echo
 # You may add  --enable-adms to the following command for adding adms generated devices 
-  ../configure --with-x --enable-xspice --enable-cider --with-readline=yes --enable-openmp --enable-sp CFLAGS="-g -m64 -O0 -Wall -Wno-unused-but-set-variable" LDFLAGS="-m64 -g"
+  ../configure --with-x --enable-xspice --enable-cider --with-readline=yes --enable-openmp CFLAGS="-g -m64 -O0 -Wall -Wno-unused-but-set-variable" LDFLAGS="-m64 -g"
 else
    cd release
    if [ $? -ne 0 ]; then  echo "cd release failed"; exit 1 ; fi
   echo "configuring for 64 bit release"
   echo
 # You may add  --enable-adms to the following command for adding adms generated devices 
-  ../configure --with-x --enable-xspice --enable-cider --with-readline=yes --enable-openmp --enable-sp --disable-debug CFLAGS="-m64 -O2" LDFLAGS="-m64 -s"
+  ../configure --with-x --enable-xspice --enable-cider --with-readline=yes --enable-openmp --disable-debug CFLAGS="-m64 -O2" LDFLAGS="-m64 -s"
 fi
 if [ $? -ne 0 ]; then  echo "../configure failed"; exit 1 ; fi
 
diff --git a/compile_min.sh b/compile_min.sh
index 0571eda07..606642aed 100755
--- a/compile_min.sh
+++ b/compile_min.sh
@@ -53,14 +53,14 @@ if test "$1" = "d"; then
   echo "configuring for 64 bit debug"
   echo
 # You may add  --enable-adms to the following command for adding adms generated devices 
-  ../configure --with-wingui --enable-xspice --enable-cider --enable-openmp --enable-sp prefix="C:/Spice64d" CFLAGS="-g -m64 -O0 -Wall -Wno-unused-but-set-variable" LDFLAGS="-g -m64"
+  ../configure --with-wingui --enable-xspice --enable-cider --enable-openmp prefix="C:/Spice64d" CFLAGS="-g -m64 -O0 -Wall -Wno-unused-but-set-variable" LDFLAGS="-g -m64"
 else
    cd release
    if [ $? -ne 0 ]; then  echo "cd release failed"; exit 1 ; fi
   echo "configuring for 64 bit release"
   echo
 # You may add  --enable-adms to the following command for adding adms generated devices 
-  ../configure --with-wingui --enable-xspice --enable-cider --enable-openmp --enable-sp --disable-debug prefix="C:/Spice64" CFLAGS="-m64 -O2" LDFLAGS="-m64 -s"
+  ../configure --with-wingui --enable-xspice --enable-cider --enable-openmp --disable-debug prefix="C:/Spice64" CFLAGS="-m64 -O2" LDFLAGS="-m64 -s"
 fi
 if [ $? -ne 0 ]; then  echo "../configure failed"; exit 1 ; fi
 
diff --git a/configure.ac b/configure.ac
index 528afb325..eb58a4efb 100644
--- a/configure.ac
+++ b/configure.ac
@@ -158,9 +158,9 @@ AC_ARG_ENABLE([adms],
 AC_ARG_ENABLE([pss],
     [AS_HELP_STRING([--enable-pss], [Enable PSS Analysis, (experimental)])])
 
-# --enable-sp: enable S Parameter Analysis
+# --disable-sp: disable S Parameter Analysis
 AC_ARG_ENABLE([sp],
-    [AS_HELP_STRING([--enable-sp], [Enable S parameter Analysis])])
+    [AS_HELP_STRING([--disable-sp], [Disable S parameter Analysis])])
 
 # --enable-relpath: Relative path for binary and data. Default is "no".
 # ngspice shared may want relative paths for spinit etc.
@@ -1166,19 +1166,21 @@ if test "x$enable_cider" = xyes; then
 fi
 
 # Add S parameter analysis to ngspice.
-if test "x$enable_sp" = xyes; then
+if test "x$enable_sp" = xno; then
+    AC_MSG_RESULT([S parameter analysis disabled])
+    has_sp=false
+else
     AC_MSG_RESULT([S parameter analysis enabled])
     AC_DEFINE([RFSPICE], [1], [S parameter analysis])
+    has_sp=true
 fi
 
+AM_CONDITIONAL([SP_WANTED], [test "x$has_sp" = xtrue])
+
+
 AM_CONDITIONAL([CIDER_WANTED], [test "x$enable_cider" = xyes])
 AM_CONDITIONAL([NUMDEV_WANTED], [test "x$enable_cider" = xyes])
-
-
 AM_CONDITIONAL([PSS_WANTED], [test "x$enable_pss" = xyes])
-
-AM_CONDITIONAL([SP_WANTED], [test "x$enable_sp" = xyes])
-
 AM_CONDITIONAL([SENSE2_WANTED], [test "x$enable_sense2" = xyes])
 
 # adms option