Index: nsf/build.sh
==================================================================
--- nsf/build.sh
+++ nsf/build.sh
@@ -31,11 +31,12 @@
 fi
 
 BUILDDIR="$(pwd)/build/nsf${NSFVERS}"
 OUTDIR="$(pwd)/out"
 INSTDIR="$(pwd)/inst"
-export NSFVERS SRC SRCURL BUILDDIR OUTDIR INSTDIR
+PATCHDIR="$(pwd)/patches"
+export NSFVERS SRC SRCURL BUILDDIR OUTDIR INSTDIR PATCHDIR
 
 # Set configure options for this sub-project
 LDFLAGS="${LDFLAGS} ${KC_NSF_LDFLAGS}"
 CFLAGS="${CFLAGS} ${KC_NSF_CFLAGS}"
 CPPFLAGS="${CPPFLAGS} ${KC_NSF_CPPFLAGS}"
@@ -72,10 +73,19 @@
 	## the GIT zip tarball does not preserve file permissions (configure)
 	rm -rf configure
 	autoconf || exit 1
     fi
 
+    # Apply patches if needed
+    for patch in "${PATCHDIR}/all"/nsf-${NSFVERS}-*.diff "${PATCHDIR}/all"/nsf-all-*.diff "${PATCHDIR}/${NSFVERS}"/nsf-${NSFVERS}-*.diff; do
+	if [ ! -f "${patch}" ]; then
+	    continue
+	fi
+        
+	echo "Applying: ${patch}"
+	${PATCH:-patch} -p1 < "${patch}"
+    done
 
     # There's a STATIC<packageInAllUpperCase>=-1,0,1
     # ... where -1 means no (i.e., shared),
     # ... 0 means try not to (try shared first, if that
     # 	  doesn't work do static),

ADDED   nsf/patches/all/nsf-all-noextern-fix.diff
Index: nsf/patches/all/nsf-all-noextern-fix.diff
==================================================================
--- nsf/patches/all/nsf-all-noextern-fix.diff
+++ nsf/patches/all/nsf-all-noextern-fix.diff
@@ -0,0 +1,23 @@
+--- nsf2.3.0/generic/nsf.h.orig	2020-09-02 17:32:45.000000000 +0200
++++ nsf2.3.0/generic/nsf.h	2020-09-02 17:34:08.000000000 +0200
+@@ -40,6 +40,20 @@
+ 
+ #include "tcl.h"
+ 
++/*
++ * Make sure EXTERN isn't defined elsewhere.
++ */
++
++#ifdef EXTERN
++#   undef EXTERN
++#endif /* EXTERN */
++
++#ifdef __cplusplus
++#   define EXTERN extern "C" TCL_STORAGE_CLASS
++#else
++#   define EXTERN extern TCL_STORAGE_CLASS
++#endif
++
+ #undef TCL_STORAGE_CLASS
+ #ifdef BUILD_nsf
+ # define TCL_STORAGE_CLASS DLLEXPORT