diff --git a/libyasm/intnum.c b/libyasm/intnum.c
index f91fff98..45da0c7a 100644
--- a/libyasm/intnum.c
+++ b/libyasm/intnum.c
@@ -435,6 +435,8 @@ intnum_calc(intnum *acc, ExprOp op, intnum *operand)
 	    if (result)
 		BitVector_Copy(result, op1);
 	    break;
+	default:
+	    InternalError(_("invalid operation in intnum calculation"));
     }
 
     /* If we were doing a bitvector computation... */
diff --git a/src/intnum.c b/src/intnum.c
index f91fff98..45da0c7a 100644
--- a/src/intnum.c
+++ b/src/intnum.c
@@ -435,6 +435,8 @@ intnum_calc(intnum *acc, ExprOp op, intnum *operand)
 	    if (result)
 		BitVector_Copy(result, op1);
 	    break;
+	default:
+	    InternalError(_("invalid operation in intnum calculation"));
     }
 
     /* If we were doing a bitvector computation... */