diff --git a/libsnark/gadgetlib1/gadgets/cpu_checkers/tinyram/tinyram_cpu_checker.tcc b/libsnark/gadgetlib1/gadgets/cpu_checkers/tinyram/tinyram_cpu_checker.tcc
index 736f365f..b0ea2d6d 100644
--- a/libsnark/gadgetlib1/gadgets/cpu_checkers/tinyram/tinyram_cpu_checker.tcc
+++ b/libsnark/gadgetlib1/gadgets/cpu_checkers/tinyram/tinyram_cpu_checker.tcc
@@ -326,12 +326,12 @@ void tinyram_cpu_checker<FieldT>::generate_r1cs_witness_other(tinyram_input_tape
     }
 
     this->pb.val(read_not1) = this->pb.val(opcode_indicators[tinyram_opcode_READ]) * (FieldT::one() - this->pb.val(arg2val->packed));
-    if (this->pb.val(read_not1) != FieldT::one())
+    if (this->pb.val(read_not1) != FieldT::zero())
     {
-        /* reading from tape other than 0 raises the flag */
+        /* reading from tape other than 1 raises the flag */
         this->pb.val(instruction_flags[tinyram_opcode_READ]) = FieldT::one();
     }
-    else
+    else if (this->pb.val(opcode_indicators[tinyram_opcode_READ]) != FieldT::zero())
     {
         /* otherwise perform the actual read */
         if (aux_it != aux_end)
diff --git a/libsnark/relations/ram_computations/rams/tinyram/tinyram_aux.cpp b/libsnark/relations/ram_computations/rams/tinyram/tinyram_aux.cpp
index 8866275e..d7845149 100644
--- a/libsnark/relations/ram_computations/rams/tinyram/tinyram_aux.cpp
+++ b/libsnark/relations/ram_computations/rams/tinyram/tinyram_aux.cpp
@@ -117,7 +117,7 @@ void ensure_tinyram_opcode_value_map()
 std::vector<tinyram_instruction> generate_tinyram_prelude(const tinyram_architecture_params &ap)
 {
     std::vector<tinyram_instruction> result;
-    const size_t increment = libff::log2(ap.w)/8;
+    const size_t increment = ap.w/8;
     const size_t mem_start = 1ul<<(ap.w-1);
     result.emplace_back(tinyram_instruction(tinyram_opcode_STOREW,  true, 0, 0, 0));         // 0: store.w 0, r0
     result.emplace_back(tinyram_instruction(tinyram_opcode_MOV,     true, 0, 0, mem_start)); // 1: mov r0, 2^{W-1}