diff --git a/.github/workflows/ticcltools.yml b/.github/workflows/ticcltools.yml
index 4c4fac1..ac0f640 100644
--- a/.github/workflows/ticcltools.yml
+++ b/.github/workflows/ticcltools.yml
@@ -40,7 +40,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, macos-14]
-        compiler: [g++, clang++]
+        compiler: [g++-12, clang++]
 
     steps:
       - name: Cancel Previous Runs
diff --git a/configure.ac b/configure.ac
index aaffe9b..8d5abd1 100644
--- a/configure.ac
+++ b/configure.ac
@@ -8,18 +8,11 @@ AC_CONFIG_SRCDIR([.])
 AC_CONFIG_MACRO_DIR([m4])
 AC_CONFIG_HEADERS([config.h])
 
-if test x"${CXXFLAGS+set}" = xset; then
-  # the user set CXXFLAGS; don't override it.
-  cxx_flags_were_set=true
-else
-  cxx_flags_were_set=false
-fi
-if $cxx_flags_were_set; then
-  CXXFLAGS=$CXXFLAGS
-fi
+AX_REQUIRE_DEFINED([AX_CXX_COMPILE_STDCXX_17])
 
 # Checks for programs.
 AC_PROG_CXX( [g++] )
+AX_CXX_COMPILE_STDCXX_17
 
 # when running tests, use CXX
 AC_LANG([C++])
diff --git a/src/Makefile.am b/src/Makefile.am
index 5bb6626..2a9e1f4 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -1,5 +1,5 @@
 AM_CPPFLAGS = -I@top_srcdir@/include
-AM_CXXFLAGS = -std=c++14 -g -W -Wall -pedantic -O3
+AM_CXXFLAGS = -std=c++17 -g -W -Wall -pedantic -O3
 
 bin_PROGRAMS = TICCL-indexer TICCL-indexerNT \
 	TICCL-LDcalc TICCL-unk TICCL-lexstat \