diff --git a/src/video/allegro_v.cpp b/src/video/allegro_v.cpp
--- a/src/video/allegro_v.cpp
+++ b/src/video/allegro_v.cpp
@@ -28,6 +28,7 @@
 #include "../thread.h"
 #include "allegro_v.h"
 #include <allegro.h>
+#include <algorithm>
 
 #include "../safeguards.h"
 
@@ -139,34 +140,25 @@ static void GetVideoModes()
 	 * cards ourselves... and we need a card to get the modes. */
 	set_gfx_mode(_fullscreen ? GFX_AUTODETECT_FULLSCREEN : GFX_AUTODETECT_WINDOWED, 640, 480, 0, 0);
 
+	_resolutions.clear();
+
 	GFX_MODE_LIST *mode_list = get_gfx_mode_list(gfx_driver->id);
 	if (mode_list == nullptr) {
-		memcpy(_resolutions, default_resolutions, sizeof(default_resolutions));
-		_num_resolutions = lengthof(default_resolutions);
+		_resolutions.assign(std::begin(default_resolutions), std::end(default_resolutions));
 		return;
 	}
 
 	GFX_MODE *modes = mode_list->mode;
 
-	int n = 0;
 	for (int i = 0; modes[i].bpp != 0; i++) {
 		uint w = modes[i].width;
 		uint h = modes[i].height;
-		if (w >= 640 && h >= 480) {
-			int j;
-			for (j = 0; j < n; j++) {
-				if (_resolutions[j].width == w && _resolutions[j].height == h) break;
-			}
+		if (w < 640 || h < 480) continue;
+		if (std::find(_resolutions.begin(), _resolutions.end(), Dimension(w, h)) != _resolutions.end()) continue;
+		_resolutions.emplace_back(w, h);
+	}
 
-			if (j == n) {
-				_resolutions[j].width  = w;
-				_resolutions[j].height = h;
-				if (++n == lengthof(_resolutions)) break;
-			}
-		}
-	}
-	_num_resolutions = n;
-	SortResolutions(_num_resolutions);
+	SortResolutions();
 
 	destroy_gfx_mode_list(mode_list);
 }
@@ -174,17 +166,15 @@ static void GetVideoModes()
 static void GetAvailableVideoMode(uint *w, uint *h)
 {
 	/* No video modes, so just try it and see where it ends */
-	if (_num_resolutions == 0) return;
+	if (_resolutions.empty()) return;
 
 	/* is the wanted mode among the available modes? */
-	for (int i = 0; i != _num_resolutions; i++) {
-		if (*w == _resolutions[i].width && *h == _resolutions[i].height) return;
-	}
+	if (std::find(_resolutions.begin(), _resolutions.end(), Dimension(*w, *h)) != _resolutions.end()) return;
 
 	/* use the closest possible resolution */
-	int best = 0;
+	uint best = 0;
 	uint delta = Delta(_resolutions[0].width, *w) * Delta(_resolutions[0].height, *h);
-	for (int i = 1; i != _num_resolutions; ++i) {
+	for (uint i = 1; i != _resolutions.size(); ++i) {
 		uint newdelta = Delta(_resolutions[i].width, *w) * Delta(_resolutions[i].height, *h);
 		if (newdelta < delta) {
 			best = i;
@@ -545,7 +535,7 @@ bool VideoDriver_Allegro::ToggleFullscre
 {
 	_fullscreen = fullscreen;
 	GetVideoModes(); // get the list of available video modes
-	if (_num_resolutions == 0 || !this->ChangeResolution(_cur_resolution.width, _cur_resolution.height)) {
+	if (_resolutions.empty() || !this->ChangeResolution(_cur_resolution.width, _cur_resolution.height)) {
 		/* switching resolution failed, put back full_screen to original status */
 		_fullscreen ^= true;
 		return false;