diff --git a/src/cocoa_monitor.m b/src/cocoa_monitor.m
index 78089419..e351088a 100644
--- a/src/cocoa_monitor.m
+++ b/src/cocoa_monitor.m
@@ -622,6 +622,13 @@ GLFWAPI CGDirectDisplayID glfwGetCocoaMonitor(GLFWmonitor* handle)
 {
     _GLFWmonitor* monitor = (_GLFWmonitor*) handle;
     _GLFW_REQUIRE_INIT_OR_RETURN(kCGNullDirectDisplay);
+
+    if (_glfw.platform.platformID != GLFW_PLATFORM_COCOA)
+    {
+        _glfwInputError(GLFW_PLATFORM_UNAVAILABLE, "Cocoa: Platform not initialized");
+        return kCGNullDirectDisplay;
+    }
+
     return monitor->ns.displayID;
 }
 
diff --git a/src/win32_monitor.c b/src/win32_monitor.c
index 13f7bfe7..4edaf2c3 100644
--- a/src/win32_monitor.c
+++ b/src/win32_monitor.c
@@ -535,6 +535,13 @@ GLFWAPI const char* glfwGetWin32Adapter(GLFWmonitor* handle)
 {
     _GLFWmonitor* monitor = (_GLFWmonitor*) handle;
     _GLFW_REQUIRE_INIT_OR_RETURN(NULL);
+
+    if (_glfw.platform.platformID != GLFW_PLATFORM_WIN32)
+    {
+        _glfwInputError(GLFW_PLATFORM_UNAVAILABLE, "Win32: Platform not initialized");
+        return NULL;
+    }
+
     return monitor->win32.publicAdapterName;
 }
 
@@ -542,6 +549,13 @@ GLFWAPI const char* glfwGetWin32Monitor(GLFWmonitor* handle)
 {
     _GLFWmonitor* monitor = (_GLFWmonitor*) handle;
     _GLFW_REQUIRE_INIT_OR_RETURN(NULL);
+
+    if (_glfw.platform.platformID != GLFW_PLATFORM_WIN32)
+    {
+        _glfwInputError(GLFW_PLATFORM_UNAVAILABLE, "Win32: Platform not initialized");
+        return NULL;
+    }
+
     return monitor->win32.publicDisplayName;
 }
 
diff --git a/src/wl_monitor.c b/src/wl_monitor.c
index df64f603..96527a48 100644
--- a/src/wl_monitor.c
+++ b/src/wl_monitor.c
@@ -259,6 +259,13 @@ GLFWAPI struct wl_output* glfwGetWaylandMonitor(GLFWmonitor* handle)
 {
     _GLFWmonitor* monitor = (_GLFWmonitor*) handle;
     _GLFW_REQUIRE_INIT_OR_RETURN(NULL);
+
+    if (_glfw.platform.platformID != GLFW_PLATFORM_WAYLAND)
+    {
+        _glfwInputError(GLFW_PLATFORM_UNAVAILABLE, "Wayland: Platform not initialized");
+        return NULL;
+    }
+
     return monitor->wl.output;
 }
 
diff --git a/src/x11_monitor.c b/src/x11_monitor.c
index ae626643..31640fb1 100644
--- a/src/x11_monitor.c
+++ b/src/x11_monitor.c
@@ -604,6 +604,13 @@ GLFWAPI RRCrtc glfwGetX11Adapter(GLFWmonitor* handle)
 {
     _GLFWmonitor* monitor = (_GLFWmonitor*) handle;
     _GLFW_REQUIRE_INIT_OR_RETURN(None);
+
+    if (_glfw.platform.platformID != GLFW_PLATFORM_X11)
+    {
+        _glfwInputError(GLFW_PLATFORM_UNAVAILABLE, "X11: Platform not initialized");
+        return None;
+    }
+
     return monitor->x11.crtc;
 }
 
@@ -611,6 +618,13 @@ GLFWAPI RROutput glfwGetX11Monitor(GLFWmonitor* handle)
 {
     _GLFWmonitor* monitor = (_GLFWmonitor*) handle;
     _GLFW_REQUIRE_INIT_OR_RETURN(None);
+
+    if (_glfw.platform.platformID != GLFW_PLATFORM_X11)
+    {
+        _glfwInputError(GLFW_PLATFORM_UNAVAILABLE, "X11: Platform not initialized");
+        return None;
+    }
+
     return monitor->x11.output;
 }