diff --git a/src/cfgparse.y b/src/cfgparse.y
index 59b22c6c..8426de0b 100644
--- a/src/cfgparse.y
+++ b/src/cfgparse.y
@@ -310,6 +310,53 @@ void kill_configerror_nagbar(bool wait_for_it) {
     waitpid(configerror_pid, NULL, 0);
 }
 
+/*
+ * Checks for duplicate key bindings (the same keycode or keysym is configured
+ * more than once). If a duplicate binding is found, a message is printed to
+ * stderr and the has_errors variable is set to true, which will start
+ * i3-nagbar.
+ *
+ */
+static void check_for_duplicate_bindings(struct context *context) {
+    Binding *bind, *current;
+    TAILQ_FOREACH(current, bindings, bindings) {
+        TAILQ_FOREACH(bind, bindings, bindings) {
+            /* Abort when we reach the current keybinding, only check the
+             * bindings before */
+            if (bind == current)
+                break;
+
+            /* Check if one is using keysym while the other is using bindsym.
+             * If so, skip. */
+            /* XXX: It should be checked at a later place (when translating the
+             * keysym to keycodes) if there are any duplicates */
+            if ((bind->symbol == NULL && current->symbol != NULL) ||
+                (bind->symbol != NULL && current->symbol == NULL))
+                continue;
+
+            /* If bind is NULL, current has to be NULL, too (see above).
+             * If the keycodes differ, it can't be a duplicate. */
+            if (bind->symbol != NULL &&
+                strcasecmp(bind->symbol, current->symbol) != 0)
+                continue;
+
+            /* Check if the keycodes or modifiers are different. If so, they
+             * can't be duplicate */
+            if (bind->keycode != current->keycode ||
+                bind->mods != current->mods)
+                continue;
+            context->has_errors = true;
+            if (current->keycode != 0) {
+                ELOG("Duplicate keybinding in config file:\n  modmask %d with keycode %d, command \"%s\"\n",
+                     current->mods, current->keycode, current->command);
+            } else {
+                ELOG("Duplicate keybinding in config file:\n  modmask %d with keysym %s, command \"%s\"\n",
+                     current->mods, current->symbol, current->command);
+            }
+        }
+    }
+}
+
 void parse_file(const char *f) {
     SLIST_HEAD(variables_head, Variable) variables = SLIST_HEAD_INITIALIZER(&variables);
     int fd, ret, read_bytes = 0;
@@ -463,6 +510,8 @@ void parse_file(const char *f) {
         exit(1);
     }
 
+    check_for_duplicate_bindings(context);
+
     if (context->has_errors) {
         start_configerror_nagbar(f);
     }