diff --git a/src/cmdparse.y b/src/cmdparse.y
index 7ce5c2df..d01ca232 100644
--- a/src/cmdparse.y
+++ b/src/cmdparse.y
@@ -436,6 +436,13 @@ restart:
 focus:
     TOK_FOCUS
     {
+        if (focused &&
+            focused->type != CT_WORKSPACE &&
+            focused->fullscreen_mode != CF_NONE) {
+            LOG("Cannot change focus while in fullscreen mode.\n");
+            break;
+        }
+
         owindow *current;
 
         if (match_is_empty(&current_match)) {
@@ -486,6 +493,13 @@ focus:
     }
     | TOK_FOCUS direction
     {
+        if (focused &&
+            focused->type != CT_WORKSPACE &&
+            focused->fullscreen_mode != CF_NONE) {
+            LOG("Cannot change focus while in fullscreen mode.\n");
+            break;
+        }
+
         int direction = $2;
         switch (direction) {
             case TOK_LEFT:
@@ -513,6 +527,13 @@ focus:
     }
     | TOK_FOCUS window_mode
     {
+        if (focused &&
+            focused->type != CT_WORKSPACE &&
+            focused->fullscreen_mode != CF_NONE) {
+            LOG("Cannot change focus while in fullscreen mode.\n");
+            break;
+        }
+
         printf("should focus: ");
 
         if ($2 == TOK_TILING)
@@ -545,6 +566,13 @@ focus:
     }
     | TOK_FOCUS level
     {
+        if (focused &&
+            focused->type != CT_WORKSPACE &&
+            focused->fullscreen_mode != CF_NONE) {
+            LOG("Cannot change focus while in fullscreen mode.\n");
+            break;
+        }
+
         if ($2 == TOK_PARENT)
             level_up();
         else level_down();
diff --git a/testcases/t/100-fullscreen.t b/testcases/t/100-fullscreen.t
index ae8c63f6..06c1411a 100644
--- a/testcases/t/100-fullscreen.t
+++ b/testcases/t/100-fullscreen.t
@@ -169,4 +169,22 @@ is(fullscreen_windows(), 0, 'amount of fullscreen windows after fullscreen comma
 # clean up the workspace so that it will be cleaned when switching away
 cmd 'kill' for (@{get_ws_content($tmp)});
 
+################################################################################
+# Verify that changing focus while in fullscreen does not work.
+################################################################################
+
+$tmp = fresh_workspace;
+
+my $other = open_window;
+is($x->input_focus, $other->id, 'other window focused');
+
+$window = open_window;
+is($x->input_focus, $window->id, 'window focused');
+
+cmd 'fullscreen';
+is($x->input_focus, $window->id, 'fullscreen window focused');
+
+cmd 'focus left';
+is($x->input_focus, $window->id, 'fullscreen window still focused');
+
 done_testing;