diff --git a/src/error.c b/src/error.c
index 0a4088e1..574f84cd 100644
--- a/src/error.c
+++ b/src/error.c
@@ -107,6 +107,8 @@ GLFWAPI const char* glfwErrorString(int error)
             return "The requested OpenGL version is unavailable";
         case GLFW_PLATFORM_ERROR:
             return "A platform-specific error occurred";
+        case GLFW_WINDOW_NOT_ACTIVE:
+            return "The specified window is not active";
     }
 
     return "ERROR: UNKNOWN ERROR TOKEN PASSED TO glfwErrorString";