diff --git a/lib/curl_sspi.c b/lib/curl_sspi.c
index 6b19b47c8..b985dbceb 100644
--- a/lib/curl_sspi.c
+++ b/lib/curl_sspi.c
@@ -36,6 +36,9 @@
 #include "memdebug.h"
 
 
+/* We use our own typedef here since some headers might lack these */
+typedef PSecurityFunctionTableA (APIENTRY *INITSECURITYINTERFACE_FN_A)(VOID);
+
 /* Handle of security.dll or secur32.dll, depending on Windows version */
 HMODULE s_hSecDll = NULL;
 
@@ -59,7 +62,7 @@ CURLcode
 Curl_sspi_global_init(void)
 {
   OSVERSIONINFO osver;
-  INIT_SECURITY_INTERFACE_A pInitSecurityInterface;
+  INITSECURITYINTERFACE_FN_A pInitSecurityInterface;
 
   /* If security interface is not yet initialized try to do this */
   if(s_hSecDll == NULL) {
@@ -84,7 +87,7 @@ Curl_sspi_global_init(void)
       return CURLE_FAILED_INIT;
 
     /* Get address of the InitSecurityInterfaceA function from the SSPI dll */
-    pInitSecurityInterface = (INIT_SECURITY_INTERFACE_A)
+    pInitSecurityInterface = (INITSECURITYINTERFACE_FN_A)
       GetProcAddress(s_hSecDll, "InitSecurityInterfaceA");
     if(! pInitSecurityInterface)
       return CURLE_FAILED_INIT;