diff --git a/src/context.c b/src/context.c
index 93b77d65..0c38e81d 100644
--- a/src/context.c
+++ b/src/context.c
@@ -87,7 +87,7 @@ static GLboolean parseGLVersion(int* api, int* major, int* minor, int* rev)
 //////                       GLFW internal API                      //////
 //////////////////////////////////////////////////////////////////////////
 
-GLboolean _glfwIsValidContextConfig(_GLFWwndconfig* wndconfig)
+GLboolean _glfwIsValidContextConfig(const _GLFWwndconfig* wndconfig)
 {
     if (wndconfig->clientAPI != GLFW_OPENGL_API &&
         wndconfig->clientAPI != GLFW_OPENGL_ES_API)
@@ -466,7 +466,7 @@ GLboolean _glfwRefreshContextAttribs(void)
     return GL_TRUE;
 }
 
-GLboolean _glfwIsValidContext(_GLFWwndconfig* wndconfig)
+GLboolean _glfwIsValidContext(const _GLFWwndconfig* wndconfig)
 {
     _GLFWwindow* window = _glfwPlatformGetCurrentContext();
 
diff --git a/src/internal.h b/src/internal.h
index 1e06460e..f0010ac3 100644
--- a/src/internal.h
+++ b/src/internal.h
@@ -743,7 +743,7 @@ GLboolean _glfwRefreshContextAttribs(void);
  *  exists and whether all relevant options have supported and non-conflicting
  *  values.
  */
-GLboolean _glfwIsValidContextConfig(_GLFWwndconfig* wndconfig);
+GLboolean _glfwIsValidContextConfig(const _GLFWwndconfig* wndconfig);
 
 /*! @brief Checks whether the current context fulfils the specified hard
  *  constraints.
@@ -752,7 +752,7 @@ GLboolean _glfwIsValidContextConfig(_GLFWwndconfig* wndconfig);
  *  otherwise.
  *  @ingroup utility
  */
-GLboolean _glfwIsValidContext(_GLFWwndconfig* wndconfig);
+GLboolean _glfwIsValidContext(const _GLFWwndconfig* wndconfig);
 
 /*! @ingroup utility
  */