diff --git a/Compiler/instructions.py b/Compiler/instructions.py
index e5679eea..55999709 100644
--- a/Compiler/instructions.py
+++ b/Compiler/instructions.py
@@ -2532,10 +2532,6 @@ class dotprods(base.VarArgsInstruction, base.DataInstruction,
                 yield 's' + field
             yield 'int'
 
-    @property
-    def gf2n_arg_format(self):
-        return self.arg_format()
-
     def get_repeat(self):
         return sum(self.args[i] // 2 - 1
                    for i, n in self.bases(iter(self.args)))
diff --git a/Compiler/types.py b/Compiler/types.py
index 71e8a613..fb5130f2 100644
--- a/Compiler/types.py
+++ b/Compiler/types.py
@@ -2210,6 +2210,7 @@ class _secret(_arithmetic_register, _secret_structure):
     @classmethod
     @set_instruction_type
     def matrix_mul(cls, A, B, n, res_params=None):
+        assert issubclass(cls, sint)
         assert len(A) % n == 0
         assert len(B) % n == 0
         size = len(A) * len(B) // n**2