diff --git a/main_sdl.m b/main_sdl.m
index db6daf9..93d6606 100644
--- a/main_sdl.m
+++ b/main_sdl.m
@@ -20,6 +20,12 @@ along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */
 
 #include <Cocoa/Cocoa.h>
+#include <SDL.h>
+
+@interface DPPCResponder : NSResponder
+@end
+
+static DPPCResponder *dppcResponder;
 
 /** @file SDL-specific main function additions for macOS hosts. */
 
@@ -37,4 +43,55 @@ void remap_appkit_menu_shortcuts(void) {
             }
         }
     }
+
+    // Add a "Grab Mouse" commamand to the Window menu.
+    NSMenuItem *windowMenuItem = [[NSApp mainMenu] itemWithTitle:@"Window"];
+    if (windowMenuItem) {
+        NSMenu *windowMenu = [windowMenuItem submenu];
+        if (windowMenu) {
+            NSMenuItem *grabMouseMenuItem = [[NSMenuItem alloc] initWithTitle:@"Grab Mouse"
+                                                                        action:@selector(grabMouse:)
+                                                                 keyEquivalent:@"g"];
+            [grabMouseMenuItem setKeyEquivalentModifierMask:NSEventModifierFlagControl];
+            [windowMenu addItem:grabMouseMenuItem];
+        }
+    }
+
+    // Insert a responder in the chain to handle the command (SDL does not
+    // expose its NSAppDelegate implementation so we can't subclass it).
+    dppcResponder = [DPPCResponder new];
+    [dppcResponder setNextResponder:[NSApp nextResponder]];
+    [NSApp setNextResponder:dppcResponder];
 }
+
+@implementation DPPCResponder
+
+- (BOOL)validateMenuItem:(NSMenuItem *)menuItem {
+    if ([menuItem action] == @selector(grabMouse:)) {
+        [menuItem setState:SDL_GetRelativeMouseMode() ? NSControlStateValueOn : NSControlStateValueOff];
+        return YES;
+    }
+    return [super validateMenuItem:menuItem];
+}
+
+- (void)grabMouse:(id)sender {
+    NSWindow *mainWindow = NSApp.mainWindow;
+    if (mainWindow) {
+        // If we're about to grab the mouse, move the mouse to the middle of the
+        // window so that SDL knows that this window is what we want coordinates
+        // to be relative to.
+        if (!SDL_GetRelativeMouseMode()) {
+            NSRect frame = mainWindow.frame;
+            NSPoint center = NSMakePoint(frame.size.width/2, frame.size.height/2);
+            center = [mainWindow convertPointToScreen:center];
+            CGWarpMouseCursorPosition(center);
+            mainWindow.subtitle = @"Mouse grabbed";
+        } else {
+            mainWindow.subtitle = @"";
+        }
+    }
+
+    SDL_SetRelativeMouseMode(!SDL_GetRelativeMouseMode());
+}
+
+@end