diff --git a/src/monitor.c b/src/monitor.c
index 80712f33..4acecd58 100644
--- a/src/monitor.c
+++ b/src/monitor.c
@@ -363,6 +363,10 @@ GLFWAPI void glfwSetGamma(GLFWmonitor* handle, float gamma)
     int i;
     unsigned short values[256];
     GLFWgammaramp ramp;
+    assert(handle != NULL);
+    assert(gamma == gamma);
+    assert(gamma >= 0.f);
+    assert(gamma <= FLT_MAX);
 
     _GLFW_REQUIRE_INIT();
 
@@ -414,6 +418,7 @@ GLFWAPI void glfwSetGammaRamp(GLFWmonitor* handle, const GLFWgammaramp* ramp)
     _GLFWmonitor* monitor = (_GLFWmonitor*) handle;
     assert(monitor != NULL);
     assert(ramp != NULL);
+    assert(ramp->size > 0);
     assert(ramp->red != NULL);
     assert(ramp->green != NULL);
     assert(ramp->blue != NULL);
diff --git a/src/vulkan.c b/src/vulkan.c
index 91ea2671..858a1e97 100644
--- a/src/vulkan.c
+++ b/src/vulkan.c
@@ -234,6 +234,8 @@ GLFWAPI int glfwVulkanSupported(void)
 
 GLFWAPI const char** glfwGetRequiredInstanceExtensions(uint32_t* count)
 {
+    assert(count != NULL);
+
     *count = 0;
 
     _GLFW_REQUIRE_INIT_OR_RETURN(NULL);
@@ -252,6 +254,7 @@ GLFWAPI GLFWvkproc glfwGetInstanceProcAddress(VkInstance instance,
                                               const char* procname)
 {
     GLFWvkproc proc;
+    assert(procname != NULL);
 
     _GLFW_REQUIRE_INIT_OR_RETURN(NULL);
 
@@ -277,6 +280,9 @@ GLFWAPI int glfwGetPhysicalDevicePresentationSupport(VkInstance instance,
                                                      VkPhysicalDevice device,
                                                      uint32_t queuefamily)
 {
+    assert(instance != VK_NULL_HANDLE);
+    assert(device != VK_NULL_HANDLE);
+
     _GLFW_REQUIRE_INIT_OR_RETURN(GLFW_FALSE);
 
     if (!_glfwInitVulkan(_GLFW_REQUIRE_LOADER))
@@ -300,6 +306,7 @@ GLFWAPI VkResult glfwCreateWindowSurface(VkInstance instance,
                                          VkSurfaceKHR* surface)
 {
     _GLFWwindow* window = (_GLFWwindow*) handle;
+    assert(instance != VK_NULL_HANDLE);
     assert(window != NULL);
     assert(surface != NULL);
 
diff --git a/src/window.c b/src/window.c
index 88377307..023cb13f 100644
--- a/src/window.c
+++ b/src/window.c
@@ -130,6 +130,8 @@ GLFWAPI GLFWwindow* glfwCreateWindow(int width, int height,
     _GLFWwindow* previous;
 
     assert(title != NULL);
+    assert(width >= 0);
+    assert(height >= 0);
 
     _GLFW_REQUIRE_INIT_OR_RETURN(NULL);
 
@@ -508,6 +510,8 @@ GLFWAPI void glfwSetWindowSize(GLFWwindow* handle, int width, int height)
 {
     _GLFWwindow* window = (_GLFWwindow*) handle;
     assert(window != NULL);
+    assert(width >= 0);
+    assert(height >= 0);
 
     _GLFW_REQUIRE_INIT();
 
@@ -566,6 +570,8 @@ GLFWAPI void glfwSetWindowAspectRatio(GLFWwindow* handle, int numer, int denom)
 {
     _GLFWwindow* window = (_GLFWwindow*) handle;
     assert(window != NULL);
+    assert(numer != 0);
+    assert(denom != 0);
 
     _GLFW_REQUIRE_INIT();
 
@@ -808,6 +814,8 @@ GLFWAPI void glfwSetWindowMonitor(GLFWwindow* wh,
     _GLFWwindow* window = (_GLFWwindow*) wh;
     _GLFWmonitor* monitor = (_GLFWmonitor*) mh;
     assert(window != NULL);
+    assert(width >= 0);
+    assert(height >= 0);
 
     _GLFW_REQUIRE_INIT();
 
@@ -961,6 +969,9 @@ GLFWAPI void glfwWaitEvents(void)
 GLFWAPI void glfwWaitEventsTimeout(double timeout)
 {
     _GLFW_REQUIRE_INIT();
+    assert(timeout == timeout);
+    assert(timeout >= 0.0);
+    assert(timeout <= DBL_MAX);
 
     if (timeout != timeout || timeout < 0.0 || timeout > DBL_MAX)
     {