diff --git a/scripts/configure b/scripts/configure
index c6d171b..001921b 100755
--- a/scripts/configure
+++ b/scripts/configure
@@ -6413,7 +6413,7 @@ fi
       # Not available on all versions:  check for include file.
       SHLIB_CFLAGS="-fpic"
       LDDL_FLAGS="-shared ${LIB_SPECS}"
-      CFLAGS="${CFLAGS} -l/usr/X11R6/include"
+      CFLAGS="${CFLAGS} -L/usr/X11R6/include"
       ;;
 
     *-netbsd*|*-openbsd*)
diff --git a/scripts/configure.in b/scripts/configure.in
index 2f951c2..601a6df 100644
--- a/scripts/configure.in
+++ b/scripts/configure.in
@@ -1120,7 +1120,7 @@ if test $usingTcl ; then
       # Not available on all versions:  check for include file.
       SHLIB_CFLAGS="-fpic"
       LDDL_FLAGS="-shared ${LIB_SPECS}"
-      CFLAGS="${CFLAGS} -l/usr/X11R6/include"
+      CFLAGS="${CFLAGS} -L/usr/X11R6/include"
       ;;
 
     *-netbsd*|*-openbsd*)