diff --git a/passes/techmap/dfflibmap.cc b/passes/techmap/dfflibmap.cc
index 0324afa84..49b980596 100644
--- a/passes/techmap/dfflibmap.cc
+++ b/passes/techmap/dfflibmap.cc
@@ -473,17 +473,19 @@ struct DfflibmapPass : public Pass {
 		find_cell_sr(libparser.ast, "$_DFFSR_PPN_", true, true, false);
 		find_cell_sr(libparser.ast, "$_DFFSR_PPP_", true, true, true);
 
-		bool keep_running = true;
-		while (keep_running) {
+		bool keep_running;
+		do {
 			keep_running = false;
-			keep_running |= expand_cellmap("$_DFF_*_", "C");
-			keep_running |= expand_cellmap("$_DFF_*??_", "C");
 			keep_running |= expand_cellmap("$_DFF_?*?_", "R");
 			keep_running |= expand_cellmap("$_DFF_??*_", "DQ");
-			keep_running |= expand_cellmap("$_DFFSR_*??_", "C");
 			keep_running |= expand_cellmap("$_DFFSR_?*?_", "S");
 			keep_running |= expand_cellmap("$_DFFSR_??*_", "R");
-		}
+		} while (keep_running);
+		do {
+			keep_running |= expand_cellmap("$_DFF_*_", "C");
+			keep_running |= expand_cellmap("$_DFF_*??_", "C");
+			keep_running |= expand_cellmap("$_DFFSR_*??_", "C");
+		} while (keep_running);
 
 		map_sr_to_arst("$_DFFSR_NNN_", "$_DFF_NN0_");
 		map_sr_to_arst("$_DFFSR_NNN_", "$_DFF_NN1_");