diff --git a/src/keyboard.c b/src/keyboard.c
index 1a624c1..c012cde 100644
--- a/src/keyboard.c
+++ b/src/keyboard.c
@@ -112,7 +112,8 @@ static void set_mods(struct keyboard *kbd, uint8_t mods)
 			 * additional control sequences.
 			 */
 			int guard = ((((kbd->last_pressed_output_code == KEYD_LEFTMETA) && mask == MOD_SUPER) ||
-					((kbd->last_pressed_output_code == KEYD_LEFTALT) && mask == MOD_ALT)) &&
+					((kbd->last_pressed_output_code == KEYD_LEFTALT) && mask == MOD_ALT) ||
+					((kbd->last_pressed_output_code == KEYD_RIGHTALT) && mask == MOD_ALT_GR)) &&
 				    !kbd->inhibit_modifier_guard &&
 				    !kbd->config.disable_modifier_guard);
 
diff --git a/t/altgr-modifier-guard.t b/t/altgr-modifier-guard.t
new file mode 100644
index 0000000..38f8551
--- /dev/null
+++ b/t/altgr-modifier-guard.t
@@ -0,0 +1,27 @@
+rightalt down
+a down
+a up
+rightalt up
+rightalt down
+rightalt up
+rightalt down
+x down
+x up
+rightalt up
+
+rightalt down
+control down
+rightalt up
+control up
+a down
+a up
+rightalt down
+control down
+rightalt up
+control up
+rightalt down
+rightalt up
+rightalt down
+x down
+x up
+rightalt up
diff --git a/t/test.conf b/t/test.conf
index 2d186aa..b2baa55 100644
--- a/t/test.conf
+++ b/t/test.conf
@@ -43,6 +43,10 @@ o = overloadt(control, a, 10)
 \ = 😄
 [ = togglem(control, macro(one))
 
+[altgr]
+
+a = a
+
 [layout2:layout]
 
 a = c