diff --git a/configure b/configure
index cb35f7154..e98b682bd 100755
--- a/configure
+++ b/configure
@@ -10265,12 +10265,18 @@ fi
 # See if we are using a compiler which allows us to change the class
 # to be used for constant strings by using the -fconstant-string-class
 # option.  If that is the case, we change it to NSConstantString.
+# Unless we are building for the apple runtime (ie only building base
+# additions library and not implementing a constant string class).
 #---------------------------------------------------------------------
-strclass_CPPFLAGS="$CPPFLAGS"
-CPPFLAGS="$CPPFLAGS -fconstant-string-class=FooConstantString"
-{ $as_echo "$as_me:$LINENO: checking if the compiler supports -fconstant-string-class" >&5
+if test "$OBJC_RUNTIME_LIB" = "nx" -o "$OBJC_RUNTIME_LIB" = "apple"; then
+  NX_CONST_STRING_OBJCFLAGS=""
+  NX_CONST_STRING_CLASS=NXConstantString
+else
+  strclass_CPPFLAGS="$CPPFLAGS"
+  CPPFLAGS="$CPPFLAGS -fconstant-string-class=FooConstantString"
+  { $as_echo "$as_me:$LINENO: checking if the compiler supports -fconstant-string-class" >&5
 $as_echo_n "checking if the compiler supports -fconstant-string-class... " >&6; }
-if test "${objc_compiler_supports_constant_string_class+set}" = set; then
+  if test "${objc_compiler_supports_constant_string_class+set}" = set; then
   $as_echo_n "(cached) " >&6
 else
   if test "$cross_compiling" = yes; then
@@ -10323,33 +10329,34 @@ fi
 
 fi
 
-if test $objc_compiler_supports_constant_string_class = yes; then
-  NX_CONST_STRING_OBJCFLAGS="-fconstant-string-class=NSConstantString"
-  NX_CONST_STRING_CLASS=NSConstantString
-  { $as_echo "$as_me:$LINENO: result: yes" >&5
+  if test $objc_compiler_supports_constant_string_class = yes; then
+    NX_CONST_STRING_OBJCFLAGS="-fconstant-string-class=NSConstantString"
+    NX_CONST_STRING_CLASS=NSConstantString
+    { $as_echo "$as_me:$LINENO: result: yes" >&5
 $as_echo "yes" >&6; }
-else
-  { $as_echo "$as_me:$LINENO: result: no" >&5
+  else
+    { $as_echo "$as_me:$LINENO: result: no" >&5
 $as_echo "no" >&6; }
-  # Check whether --enable-nxconstantstring was given.
+    # Check whether --enable-nxconstantstring was given.
 if test "${enable_nxconstantstring+set}" = set; then
   enableval=$enable_nxconstantstring;
 else
   enable_nxconstantstring=no
 fi
 
-  if test $enable_nxconstantstring = yes; then
-    NX_CONST_STRING_OBJCFLAGS=""
-    NX_CONST_STRING_CLASS=NXConstantString
-    { $as_echo "$as_me:$LINENO: WARNING: You have enabled the use of NXConstantString as the string class in gnustep-base.  The objective-c runtime library typically implements its own class of the same name, so you must either enforce a link order which ensures that the gnustep-base implementation is used, or (better) you must remove the class from the runtime library!" >&5
+    if test $enable_nxconstantstring = yes; then
+      NX_CONST_STRING_OBJCFLAGS=""
+      NX_CONST_STRING_CLASS=NXConstantString
+      { $as_echo "$as_me:$LINENO: WARNING: You have enabled the use of NXConstantString as the string class in gnustep-base.  The objective-c runtime library typically implements its own class of the same name, so you must either enforce a link order which ensures that the gnustep-base implementation is used, or (better) you must remove the class from the runtime library!" >&5
 $as_echo "$as_me: WARNING: You have enabled the use of NXConstantString as the string class in gnustep-base.  The objective-c runtime library typically implements its own class of the same name, so you must either enforce a link order which ensures that the gnustep-base implementation is used, or (better) you must remove the class from the runtime library!" >&2;}
-  else
-    { { $as_echo "$as_me:$LINENO: error: Your compiler does not appear to implement the -fconstant-string-class option needed for support of strings.  Please check for a more recent version or consider using --enable-nxconstantstring" >&5
+    else
+      { { $as_echo "$as_me:$LINENO: error: Your compiler does not appear to implement the -fconstant-string-class option needed for support of strings.  Please check for a more recent version or consider using --enable-nxconstantstring" >&5
 $as_echo "$as_me: error: Your compiler does not appear to implement the -fconstant-string-class option needed for support of strings.  Please check for a more recent version or consider using --enable-nxconstantstring" >&2;}
    { (exit 1); exit 1; }; }
+    fi
   fi
+  CPPFLAGS="$strclass_CPPFLAGS"
 fi
-CPPFLAGS="$strclass_CPPFLAGS"
 
 
 
diff --git a/configure.ac b/configure.ac
index 4a037caf8..eb24a4c0d 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1461,35 +1461,42 @@ fi
 # See if we are using a compiler which allows us to change the class
 # to be used for constant strings by using the -fconstant-string-class
 # option.  If that is the case, we change it to NSConstantString.
+# Unless we are building for the apple runtime (ie only building base
+# additions library and not implementing a constant string class).
 #---------------------------------------------------------------------
-strclass_CPPFLAGS="$CPPFLAGS"
-CPPFLAGS="$CPPFLAGS -fconstant-string-class=FooConstantString"
-AC_MSG_CHECKING(if the compiler supports -fconstant-string-class)
-AC_CACHE_VAL(objc_compiler_supports_constant_string_class,
-  AC_TRY_RUN([#include "$srcdir/config/config.constant-string-class.m"],
-  objc_compiler_supports_constant_string_class=yes,
-  objc_compiler_supports_constant_string_class=no,
-  objc_compiler_supports_constant_string_class=no)
-)
-if test $objc_compiler_supports_constant_string_class = yes; then
-  NX_CONST_STRING_OBJCFLAGS="-fconstant-string-class=NSConstantString"
-  NX_CONST_STRING_CLASS=NSConstantString
-  AC_MSG_RESULT(yes)
+if test "$OBJC_RUNTIME_LIB" = "nx" -o "$OBJC_RUNTIME_LIB" = "apple"; then
+  NX_CONST_STRING_OBJCFLAGS=""
+  NX_CONST_STRING_CLASS=NXConstantString
 else
-  AC_MSG_RESULT(no)
-  AC_ARG_ENABLE(nxconstantstring,
-      [  --enable-nxconstantstring
-	    Enables the use of the NXConstantString class for old compilers.],,
-      enable_nxconstantstring=no)
-  if test $enable_nxconstantstring = yes; then
-    NX_CONST_STRING_OBJCFLAGS=""
-    NX_CONST_STRING_CLASS=NXConstantString
-    AC_MSG_WARN([You have enabled the use of NXConstantString as the string class in gnustep-base.  The objective-c runtime library typically implements its own class of the same name, so you must either enforce a link order which ensures that the gnustep-base implementation is used, or (better) you must remove the class from the runtime library!])
+  strclass_CPPFLAGS="$CPPFLAGS"
+  CPPFLAGS="$CPPFLAGS -fconstant-string-class=FooConstantString"
+  AC_MSG_CHECKING(if the compiler supports -fconstant-string-class)
+  AC_CACHE_VAL(objc_compiler_supports_constant_string_class,
+    AC_TRY_RUN([#include "$srcdir/config/config.constant-string-class.m"],
+    objc_compiler_supports_constant_string_class=yes,
+    objc_compiler_supports_constant_string_class=no,
+    objc_compiler_supports_constant_string_class=no)
+  )
+  if test $objc_compiler_supports_constant_string_class = yes; then
+    NX_CONST_STRING_OBJCFLAGS="-fconstant-string-class=NSConstantString"
+    NX_CONST_STRING_CLASS=NSConstantString
+    AC_MSG_RESULT(yes)
   else
-    AC_MSG_ERROR([Your compiler does not appear to implement the -fconstant-string-class option needed for support of strings.  Please check for a more recent version or consider using --enable-nxconstantstring])
+    AC_MSG_RESULT(no)
+    AC_ARG_ENABLE(nxconstantstring,
+        [  --enable-nxconstantstring
+	    Enables the use of the NXConstantString class for old compilers.],,
+        enable_nxconstantstring=no)
+    if test $enable_nxconstantstring = yes; then
+      NX_CONST_STRING_OBJCFLAGS=""
+      NX_CONST_STRING_CLASS=NXConstantString
+      AC_MSG_WARN([You have enabled the use of NXConstantString as the string class in gnustep-base.  The objective-c runtime library typically implements its own class of the same name, so you must either enforce a link order which ensures that the gnustep-base implementation is used, or (better) you must remove the class from the runtime library!])
+    else
+      AC_MSG_ERROR([Your compiler does not appear to implement the -fconstant-string-class option needed for support of strings.  Please check for a more recent version or consider using --enable-nxconstantstring])
+    fi
   fi
+  CPPFLAGS="$strclass_CPPFLAGS"
 fi
-CPPFLAGS="$strclass_CPPFLAGS"
 
 AC_SUBST(NX_CONST_STRING_OBJCFLAGS)
 AC_SUBST(NX_CONST_STRING_CLASS)