diff --git a/src/86box.c b/src/86box.c
index 132551e79..3589ec45e 100644
--- a/src/86box.c
+++ b/src/86box.c
@@ -28,6 +28,8 @@
 #include <string.h>
 #include <time.h>
 #include <wchar.h>
+#include <stdatomic.h>
+
 #ifndef _WIN32
 #include <pwd.h>
 #endif
@@ -96,7 +98,7 @@
 /* Stuff that used to be globally declared in plat.h but is now extern there
    and declared here instead. */
 int		dopause;		/* system is paused */
-int		doresize;			/* screen resize requested */
+atomic_flag		doresize;			/* screen resize requested */
 volatile int		is_quit;				/* system exit requested */
 uint64_t	timer_freq;
 char        emu_version[200];		/* version ID string */
@@ -1285,9 +1287,7 @@ set_screen_size(int x, int y)
 
     /* If the resolution has changed, let the main thread handle it. */
     if ((owsx != scrnsz_x) || (owsy != scrnsz_y))
-	doresize = 1;
-    else
-	doresize = 0;
+		atomic_flag_clear(&doresize);
 }
 
 
diff --git a/src/include/86box/plat.h b/src/include/86box/plat.h
index 2fd4574ce..78795d757 100644
--- a/src/include/86box/plat.h
+++ b/src/include/86box/plat.h
@@ -63,13 +63,18 @@ extern int strnicmp(const char* s1, const char* s2, size_t n);
 
 
 #ifdef __cplusplus
+#include <atomic>
+#define atomic_flag_t std::atomic_flag
 extern "C" {
+#else
+#include <stdatomic.h>
+#define atomic_flag_t atomic_flag
 #endif
 
 /* Global variables residing in the platform module. */
 extern int	dopause,			/* system is paused */
-		doresize,			/* screen resize requested */
 		mouse_capture;			/* mouse is captured in app */
+extern atomic_flag_t doresize;			/* screen resize requested */
 extern volatile int	is_quit;				/* system exit requested */
 
 #ifdef MTR_ENABLED
diff --git a/src/unix/unix.c b/src/unix/unix.c
index 47a65944d..c583f7f50 100644
--- a/src/unix/unix.c
+++ b/src/unix/unix.c
@@ -18,6 +18,7 @@
 #include <inttypes.h>
 #include <dlfcn.h>
 #include <wchar.h>
+#include <stdatomic.h>
 
 #include <86box/86box.h>
 #include <86box/keyboard.h>
@@ -531,12 +532,11 @@ main_thread(void *param)
 		SDL_Delay(1);
 
 	/* If needed, handle a screen resize. */
-	if (doresize && !video_fullscreen && !is_quit) {
+	if (!atomic_flag_test_and_set(&doresize) && !video_fullscreen && !is_quit) {
 		if (vid_resize & 2)
 			plat_resize(fixed_size_x, fixed_size_y);
 		else
 			plat_resize(scrnsz_x, scrnsz_y);
-		doresize = 0;
 	}
     }
 
diff --git a/src/win/win.c b/src/win/win.c
index 9298aa7fd..7f35f6d0b 100644
--- a/src/win/win.c
+++ b/src/win/win.c
@@ -35,6 +35,7 @@
 #include <direct.h>
 #include <wchar.h>
 #include <io.h>
+#include <stdatomic.h>
 #define HAVE_STDARG_H
 #include <86box/86box.h>
 #include <86box/config.h>
@@ -549,12 +550,11 @@ main_thread(void *param)
 		// Sleep(1);
 
 	/* If needed, handle a screen resize. */
-	if (doresize && !video_fullscreen && !is_quit) {
+	if (!atomic_flag_test_and_set(&doresize) && !video_fullscreen && !is_quit) {
 		if (vid_resize & 2)
 			plat_resize(fixed_size_x, fixed_size_y);
 		else
 			plat_resize(scrnsz_x, scrnsz_y);
-		doresize = 0;
 	}
     }
 
@@ -1161,7 +1161,7 @@ plat_setfullscreen(int on)
     video_fullscreen &= 1;
     video_force_resize_set(1);
     if (!(on & 1))
-	doresize = 1;
+        atomic_flag_clear(&doresize);
 
     win_mouse_init();
 
diff --git a/src/win/win_specify_dim.c b/src/win/win_specify_dim.c
index d4727c68b..96ae0403c 100644
--- a/src/win/win_specify_dim.c
+++ b/src/win/win_specify_dim.c
@@ -133,7 +133,7 @@ SpecifyDimensionsDialogProcedure(HWND hdlg, UINT message, WPARAM wParam, LPARAM
 
 				scrnsz_x = fixed_size_x;
 				scrnsz_y = fixed_size_y;
-				doresize = 1;
+				atomic_flag_clear(&doresize);
 
 				GetWindowRect(hwndMain, &r);
 
diff --git a/src/win/win_ui.c b/src/win/win_ui.c
index 5b1e8b809..c6a8983a6 100644
--- a/src/win/win_ui.c
+++ b/src/win/win_ui.c
@@ -671,7 +671,7 @@ MainWindowProcedure(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
 
 				scrnsz_x = unscaled_size_x;
 				scrnsz_y = unscaled_size_y;
-				doresize = 1;
+				atomic_flag_clear(&doresize);
 				config_save();
 				break;
 
@@ -770,7 +770,7 @@ MainWindowProcedure(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
 				reset_screen_size();
 				device_force_redraw();
 				video_force_resize_set(1);
-				doresize = 1;
+				atomic_flag_clear(&doresize);
 				config_save();
 				break;
 
@@ -785,7 +785,7 @@ MainWindowProcedure(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
 			case IDM_VID_HIDPI:
 				dpi_scale = !dpi_scale;
 				CheckMenuItem(hmenu, IDM_VID_HIDPI, dpi_scale ? MF_CHECKED : MF_UNCHECKED);
-				doresize = 1;
+				atomic_flag_clear(&doresize);
 				config_save();
 				break;
 				
@@ -946,7 +946,7 @@ MainWindowProcedure(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
 			else
 				ResizeWindowByClientArea(hwndMain, temp_x, temp_y + sbar_height);
 		} else if (!user_resize)
-			doresize = 1;
+			atomic_flag_clear(&doresize);
 		break;
 
 	case WM_WINDOWPOSCHANGED:
@@ -991,13 +991,13 @@ MainWindowProcedure(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
 				if (temp_x != scrnsz_x || temp_y != scrnsz_y) {
 					scrnsz_x = temp_x;
 					scrnsz_y = temp_y;
-					doresize = 1;
+					atomic_flag_clear(&doresize);
 				}
 			} else {
 				if (rect.right != scrnsz_x || rect.bottom != scrnsz_y) {
 					scrnsz_x = rect.right;
 					scrnsz_y = rect.bottom;
-					doresize = 1;
+					atomic_flag_clear(&doresize);
 				}
 			}
 
@@ -1159,7 +1159,7 @@ MainWindowProcedure(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
 		/* If window is not resizable, then tell the main thread to
 		   resize it, as sometimes, moves can mess up the window size. */
 		if (!vid_resize)
-			doresize = 1;
+			atomic_flag_clear(&doresize);
 		break;
     }