fix-nc-calling-convention.diff

diff --git a/src/core/nativecall_dyncall.c b/src/core/nativecall_dyncall.c
index 80616e333..5edaf7d7e 100644
--- a/src/core/nativecall_dyncall.c
+++ b/src/core/nativecall_dyncall.c
@@ -6,6 +6,11 @@
 /* Maps a calling convention name to an ID. */
 MVMint16 MVM_nativecall_get_calling_convention(MVMThreadContext *tc, MVMString *name) {
     MVMint16 result = DC_CALL_C_DEFAULT;
+#ifdef _WIN64
+    result = DC_CALL_C_X64_WIN64;
+#elif defined(__x86_64__)
+    result = DC_CALL_C_X64_SYSV;
+#else
     if (name && MVM_string_graphs(tc, name) > 0) {
         char *cname = MVM_string_utf8_encode_C_string(tc, name);
         if (strcmp(cname, "cdecl") == 0)
@@ -16,8 +21,6 @@ MVMint16 MVM_nativecall_get_calling_convention(MVMThreadContext *tc, MVMString *
             result = DC_CALL_C_X86_WIN32_THIS_GNU;
         else if (strcmp(cname, "thisms") == 0)
             result = DC_CALL_C_X86_WIN32_THIS_MS;
-        else if (strcmp(cname, "stdcall") == 0)
-            result = DC_CALL_C_X64_WIN64;
         else {
             char *waste[] = { cname, NULL };
             MVM_exception_throw_adhoc_free(tc, waste,
@@ -25,6 +28,7 @@ MVMint16 MVM_nativecall_get_calling_convention(MVMThreadContext *tc, MVMString *
         }
         MVM_free(cname);
     }
+#endif
     return result;
 }