diff --git a/passes/cmds/splitfanout.cc b/passes/cmds/splitfanout.cc
index 4e853e286..664cc1d4d 100644
--- a/passes/cmds/splitfanout.cc
+++ b/passes/cmds/splitfanout.cc
@@ -80,7 +80,7 @@ struct SplitfanoutWorker
 				outsig = conn.second;
 			}
 		if (output_count != 1) {
-			log("Skipping %s cell %s/%s with %d output ports.\n", log_id(cell->type), log_id(module), log_id(cell), output_count);
+			log_debug("Skipping %s cell %s/%s with %d output ports.\n", log_id(cell->type), log_id(module), log_id(cell), output_count);
 			return 0;
 		}
 		
@@ -88,7 +88,7 @@ struct SplitfanoutWorker
 		auto bit_users = bit_users_db[outsig[0]];
 		for (int i = 0; i < GetSize(outsig); i++) {
 			if (bit_users_db[outsig[i]] != bit_users) {
-				log("Skipping %s cell %s/%s with bit-split output.\n", log_id(cell->type), log_id(module), log_id(cell));
+				log_debug("Skipping %s cell %s/%s with bit-split output.\n", log_id(cell->type), log_id(module), log_id(cell));
 				return 0;
 			}
 		}
@@ -98,7 +98,7 @@ struct SplitfanoutWorker
 			return 0;
 
 		// Iterate over bit users and create a new cell for each one
-		log("Splitting %s cell %s/%s into %d copies based on fanout\n", log_id(cell->type), log_id(module), log_id(cell), GetSize(bit_users)-1);
+		log_debug("Splitting %s cell %s/%s into %d copies based on fanout\n", log_id(cell->type), log_id(module), log_id(cell), GetSize(bit_users)-1);
 		int foi = 0;
 		cell->unsetPort(outport);
 		for (auto bit_user : bit_users)
diff --git a/passes/opt/opt_balance_tree.cc b/passes/opt/opt_balance_tree.cc
index c28cc75f5..fff028957 100644
--- a/passes/opt/opt_balance_tree.cc
+++ b/passes/opt/opt_balance_tree.cc
@@ -101,7 +101,7 @@ struct OptBalanceTreeWorker {
 	void find_chain_start_cells() {
 		for (auto cell : candidate_cells) {
 			// Log candidate cell
-			log("Considering %s (%s)\n", log_id(cell), log_id(cell->type));
+			log_debug("Considering %s (%s)\n", log_id(cell), log_id(cell->type));
 
 			// Get signals for cell ports
 			SigSpec a_sig = sigmap(cell->getPort(ID::A));
@@ -172,7 +172,7 @@ struct OptBalanceTreeWorker {
 				}
 				cell->setPort(inport, inport_sig);
 				cell->setParam(inport_width, GetSize(inport_sig));
-				log("Width reduced %s/%s by %d bits\n", log_id(cell), log_id(inport), bits_removed);
+				log_debug("Width reduced %s/%s by %d bits\n", log_id(cell), log_id(inport), bits_removed);
 			}
 
 			// Record number of bits removed from output
@@ -194,7 +194,7 @@ struct OptBalanceTreeWorker {
 			}
 			cell->setPort(ID::Y, y_sig);
 			cell->setParam(ID::Y_WIDTH, GetSize(y_sig));
-			log("Width reduced %s/Y by %d bits\n", log_id(cell), bits_removed);
+			log_debug("Width reduced %s/Y by %d bits\n", log_id(cell), bits_removed);
 		}
 	}
 
@@ -207,7 +207,7 @@ struct OptBalanceTreeWorker {
 		Cell *mid_cell = chain[GetSize(chain) / 2];
 		Cell *midnext_cell = chain[GetSize(chain) / 2 + 1];
 		Cell *end_cell = chain.back();
-		log("Balancing chain of %d cells: mid=%s, midnext=%s, endcell=%s\n",
+		log_debug("Balancing chain of %d cells: mid=%s, midnext=%s, endcell=%s\n",
 		    GetSize(chain), log_id(mid_cell), log_id(midnext_cell), log_id(end_cell));
 
 		// Get mid signals