diff --git a/Makefile.config.in b/Makefile.config.in
index 21c89845..0c10c35e 100644
--- a/Makefile.config.in
+++ b/Makefile.config.in
@@ -185,6 +185,7 @@ CONFIG_ZSTD = @CONFIG_ZSTD@
 DEFS = @DEFS@
 CFLAGS = @CFLAGS@
 CPPFLAGS = @CPPFLAGS@
+CXXFLAGS = @CXXFLAGS@
 LDFLAGS = @LDFLAGS@
 LIBS = @LIBS@
 
@@ -193,6 +194,8 @@ INCLUDES = -I$(top_builddir) -I$(top_srcdir)/src
 
 COMPILE = $(CC) $(DEFS) $(INCLUDES) $(CPPFLAGS) $(CFLAGS)
 
+COMPILE_CXX = $(CXX) $(DEFS) $(INCLUDES) $(CPPFLAGS) $(CFLAGS) $(CXXFLAGS)
+
 MAKE_COLOR = @MAKE_COLOR@
 
 LIB_O_NAME = lib.o
diff --git a/Makefile.lib b/Makefile.lib
index 4a6a9f95..5a0e1bbd 100644
--- a/Makefile.lib
+++ b/Makefile.lib
@@ -55,6 +55,11 @@ quiet_cmd_compile = '      [$(CC_COLOR)CC$(END_COLOR)]   $(RELPATH)$@'
  masq_cmd_compile = $(COMPILE) -o $(@) -c $< $(2)
       cmd_compile = $(COMPILE) -o $(@) -MD -MF .deps/$(*F).pp -c $< $(2)
 
+quiet_cmd_compilecxx = '      [$(CC_COLOR)CXX$(END_COLOR)]   $(RELPATH)$@'
+ masq_cmd_compilecxx = $(COMPILE_CXX) -o $(@) -c $< $(2)
+      cmd_compilecxx = $(COMPILE_CXX) -o $(@) -MD -MF .deps/$(*F).pp -c $< $(2)
+
+
 # Rule to compile a set of .o files into one .o file
 quiet_cmd_ld_objs = "      [$(LD_COLOR)LD$(END_COLOR)]   $(RELPATH)$@"
       cmd_ld_objs = $(LD) -r -o $@ $(filter $(OBJS), $^) \
@@ -62,7 +67,7 @@ quiet_cmd_ld_objs = "      [$(LD_COLOR)LD$(END_COLOR)]   $(RELPATH)$@"
 			    `test -e $(subdir)/$(LIB_O_NAME) && echo $(subdir)/$(LIB_O_NAME)`)
 
    quiet_cmd_link = '    [$(LINK_COLOR)LINK$(END_COLOR)]   $(RELPATH)$@'
-         cmd_link = $(CC) $(CFLAGS) $(LDFLAGS) -o $@ $^ $(LIBS)
+         cmd_link = $(CXX) $(CFLAGS) $(LDFLAGS) -o $@ $^ $(LIBS)
 
  quiet_cmd_sparse = '    [SPARSE]   $(RELPATH)$(2)'
        cmd_sparse = $(SPARSE) $(DEFS) $(INCLUDES) $(CPPFLAGS) $(CFLAGS) $(SPARSE_FLAGS) $(2)
@@ -140,7 +145,7 @@ endif
 	fi
 
 %.obj: $(srcdir)%.cpp
-	$(call mcmd,compile)
+	$(call mcmd,compilecxx)
 	@-if test -e .deps/$(*F).pp; then \
 		cp .deps/$(*F).pp .deps/$(*F).P; \
 		tr ' ' '\012' < .deps/$(*F).pp \
diff --git a/configure.ac b/configure.ac
index a019fc88..e5760a3f 100644
--- a/configure.ac
+++ b/configure.ac
@@ -61,9 +61,6 @@ echo "Feature summary:" > features.log
 
 AC_PROG_CC
 AC_PROG_CXX
-if test x"$CC" = x"$CXX"; then
-    AC_LANG(C++)
-fi
 AC_CHECK_TOOL([LD], [ld])
 AC_PROG_AWK
 AC_PATH_PROGS(AWK, "$AWK")
@@ -757,7 +754,6 @@ if test "x$CONFIG_SPIDERMONKEY" = xyes ||
 		SPIDERMONKEY_CFLAGS="$($PKG_CONFIG $pkg_config_static --cflags $package) $DB_LOCALSTORAGE_CFLAGS $XMLPLUSPLUS_CFLAGS"
 
 		LIBS="$SPIDERMONKEY_LIBS $LIBS_X"
-		CFLAGS="$CFLAGS_X $SPIDERMONKEY_CFLAGS"
 		CPPFLAGS="$CPPFLAGS_X $SPIDERMONKEY_CFLAGS"
 		SPIDERMONKEY_FOUND=yes
 		AC_MSG_RESULT([yes])
@@ -799,6 +795,8 @@ else
 	CONFIG_SCRIPTING_SPIDERMONKEY=no
 fi
 
+CXXFLAGS="$CXXFLAGS -fpermissive -Wno-sign-compare -std=gnu++17"
+
 if test "x$CONFIG_ECMASCRIPT_SMJS" = xyes ||
    test "x$CONFIG_SCRIPTING_SPIDERMONKEY" = xyes; then
 	LIBS="$LIBS $SPIDERMONKEY_LIBS"
@@ -806,7 +804,7 @@ if test "x$CONFIG_ECMASCRIPT_SMJS" = xyes ||
 	AC_SUBST(SPIDERMONKEY_CFLAGS)
 	AC_SUBST(CONFIG_SPIDERMONKEY)
 	AC_SUBST(CONFIG_XML)
-	CFLAGS="$CFLAGS -fpermissive -Wno-sign-compare -std=gnu++17 $SPIDERMONKEY_CFLAGS"
+	CXXFLAGS="$CXXFLAGS $SPIDERMONKEY_CFLAGS"
 fi
 
 if test "x$CONFIG_QUICKJS" = xyes; then
@@ -814,7 +812,6 @@ if test "x$CONFIG_QUICKJS" = xyes; then
 	EL_CONFIG(CONFIG_QUICKJS, [quickjs])
 	AC_SUBST(CONFIG_QUICKJS)
 	AC_SUBST(CONFIG_XML)
-	CFLAGS="$CFLAGS -fpermissive -Wno-sign-compare -std=gnu++17"
 fi
 # ===================================================================
 # Check for Guile, optional even if installed.
@@ -1966,6 +1963,7 @@ fi
 AC_SUBST(GETTEXT_CFLAGS)
 EL_LOG_CONFIG(CFLAGS, [Compiler flags (CFLAGS)], [])
 EL_LOG_CONFIG(CPPFLAGS, [Preprocessor flags (CPPFLAGS)], [])
+EL_LOG_CONFIG(CXXFLAGS, [C++ compiler flags (CXXFLAGS)], [])
 EL_LOG_CONFIG(LDFLAGS, [Linker flags (LDFLAGS)], [])
 EL_LOG_CONFIG(LIBS, [Library flags (LIBS)], [])