--- a/src/gui/Makefile.am	2023-05-07 17:28:07.963906346 -0400
+++ b/src/gui/Makefile.am	2023-05-07 17:28:11.158866027 -0400
@@ -1,9 +1,9 @@
 AM_CPPFLAGS = -I$(top_srcdir)/include
 
 noinst_LIBRARIES = libgui.a
-libgui_a_SOURCES = sdlmain.cpp sdl_mapper.cpp dosbox_logo.h \
+libgui_a_SOURCES = sdlmain.cpp sdl_mapper.cpp cpp_compat.h dosbox_logo.h \
 	render.cpp render_scalers.cpp render_scalers.h \
 	render_templates.h render_loops.h render_simple.h \
 	render_templates_sai.h render_templates_hq.h \
 	render_templates_hq2x.h render_templates_hq3x.h \
 	midi.cpp midi_win32.h midi_oss.h midi_coreaudio.h midi_alsa.h \
--- a/src/gui/render_templates_sai.h	2023-05-07 17:22:19.173307921 -0400
+++ b/src/gui/render_templates_sai.h	2023-05-07 17:22:55.911844297 -0400
@@ -14,10 +14,12 @@
  *  You should have received a copy of the GNU General Public License along
  *  with this program; if not, write to the Free Software Foundation, Inc.,
  *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  */
 
+#include "cpp_compat.h"
+
 static inline int conc2d(GetResult,SBPP)(PTYPE A, PTYPE B, PTYPE C, PTYPE D) {
 	const bool ac = (A==C);
 	const bool bc = (B==C);
 	const int x1 = ac;
 	const int y1 = (bc & !ac);
@@ -41,11 +43,11 @@ inline void conc2d(Super2xSaI,SBPP)(PTYP
 	if (C7 == C5 && C4 != C8) {
 		line1[1] = line0[1] = C7;
 	} else if (C4 == C8 && C7 != C5) {
 		line1[1] = line0[1] = C4;
 	} else if (C4 == C8 && C7 == C5) {
-		register int r = 0;
+		REGISTER int r = 0;
 		r += conc2d(GetResult,SBPP)(C5,C4,C6,D1);
 		r += conc2d(GetResult,SBPP)(C5,C4,C3,C1);
 		r += conc2d(GetResult,SBPP)(C5,C4,D2,D5);
 		r += conc2d(GetResult,SBPP)(C5,C4,C2,D4);
 
@@ -125,11 +127,11 @@ inline void conc2d(SuperEagle,SBPP)(PTYP
 				line1[0] = interp_w2(C4,C7,3U,1U);
 			} else {
 				line1[0] = interp_w2(C7,C8,1U,1U);
 			}
 		} else {
-			register int r = 0;
+			REGISTER int r = 0;
 			r += conc2d(GetResult,SBPP)(C5,C4,C6,D1);
 			r += conc2d(GetResult,SBPP)(C5,C4,C3,C1);
 			r += conc2d(GetResult,SBPP)(C5,C4,D2,D5);
 			r += conc2d(GetResult,SBPP)(C5,C4,C2,D4);
 
@@ -183,11 +185,11 @@ inline void conc2d(_2xSaI,SBPP)(PTYPE *
 		if (C4 == C5) {
 			line0[1] = C4;
 			line1[0] = C4;
 			line1[1] = C4;
 		} else {
-			register int r = 0;
+			REGISTER int r = 0;
 			r += conc2d(GetResult,SBPP)(C4,C5,C3,C1);
 			r -= conc2d(GetResult,SBPP)(C5,C4,D4,C2);
 			r -= conc2d(GetResult,SBPP)(C5,C4,C6,D1);
 			r += conc2d(GetResult,SBPP)(C4,C5,D5,D2);
 
--- /dev/null	2023-04-17 21:04:02.077579196 -0400
+++ b/src/gui/cpp_compat.h	2023-05-07 17:25:20.687017303 -0400
@@ -0,0 +1,10 @@
+#ifndef DOSBOX_CPP_COMPAT_H
+#define DOSBOX_CPP_COMPAT_H
+
+#if __cplusplus < 201703L
+#define REGISTER register
+#else
+#define REGISTER
+#endif
+
+#endif