diff --git a/configure b/configure
index 4da010a5c..47601edf6 100755
--- a/configure
+++ b/configure
@@ -2416,7 +2416,7 @@ if test "$user_localdirs" = 1; then
      fi
    if test -d /usr/local/include; then
      CFLAGS="$CFLAGS -I/usr/local/include"
-     CXXFLAGS="$CFLAGS -I/usr/local/include"
+     CXXFLAGS="$CXXFLAGS -I/usr/local/include"
    fi
 fi
 
diff --git a/configure.ac b/configure.ac
index ce8322631..69a04f36a 100644
--- a/configure.ac
+++ b/configure.ac
@@ -27,7 +27,7 @@ if test "$user_localdirs" = 1; then
      fi
    if test -d /usr/local/include; then
      CFLAGS="$CFLAGS -I/usr/local/include"
-     CXXFLAGS="$CFLAGS -I/usr/local/include"
+     CXXFLAGS="$CXXFLAGS -I/usr/local/include"
    fi
 fi