diff --git a/passes/proc/proc_dff.cc b/passes/proc/proc_dff.cc
index a4c7d927c..a30cdd5ad 100644
--- a/passes/proc/proc_dff.cc
+++ b/passes/proc/proc_dff.cc
@@ -53,6 +53,16 @@ RTLIL::SigSpec find_any_lvalue(const RTLIL::Process *proc)
 	return lvalue;
 }
 
+void transfer_wire_sources(const SigSpec& sig, Cell* cell)
+{
+	pool<std::string> sources;
+	for (auto chunk : sig.chunks())
+		if (chunk.wire && chunk.wire->has_attribute(ID::src))
+			sources.insert(chunk.wire->attributes[ID::src].decode_string());
+	if (!sources.empty())
+		cell->add_strpool_attribute(ID::src, sources);
+}
+
 void gen_dffsr_complex(RTLIL::Module *mod, RTLIL::SigSpec sig_d, RTLIL::SigSpec sig_q, RTLIL::SigSpec clk, bool clk_polarity,
 		std::vector<std::pair<RTLIL::SigSpec, RTLIL::SyncRule*>> &async_rules, RTLIL::Process *proc)
 {
@@ -83,6 +93,7 @@ void gen_dffsr_complex(RTLIL::Module *mod, RTLIL::SigSpec sig_d, RTLIL::SigSpec
 
 	RTLIL::Cell *cell = mod->addDffsr(sstr.str(), clk, sig_sr_set, sig_sr_clr, sig_d, sig_q, clk_polarity);
 	cell->attributes = proc->attributes;
+	transfer_wire_sources(sig_q, cell);
 
 	log("  created %s cell `%s' with %s edge clock and multiple level-sensitive resets.\n",
 			cell->type.c_str(), cell->name.c_str(), clk_polarity ? "positive" : "negative");
@@ -96,6 +107,7 @@ void gen_aldff(RTLIL::Module *mod, RTLIL::SigSpec sig_in, RTLIL::SigSpec sig_set
 
 	RTLIL::Cell *cell = mod->addCell(sstr.str(), ID($aldff));
 	cell->attributes = proc->attributes;
+	transfer_wire_sources(sig_out, cell);
 
 	cell->parameters[ID::WIDTH] = RTLIL::Const(sig_in.size());
 	cell->parameters[ID::ALOAD_POLARITY] = RTLIL::Const(set_polarity, 1);
@@ -118,6 +130,7 @@ void gen_dff(RTLIL::Module *mod, RTLIL::SigSpec sig_in, RTLIL::Const val_rst, RT
 
 	RTLIL::Cell *cell = mod->addCell(sstr.str(), clk.empty() ? ID($ff) : arst ? ID($adff) : ID($dff));
 	cell->attributes = proc->attributes;
+	transfer_wire_sources(sig_out, cell);
 
 	cell->parameters[ID::WIDTH] = RTLIL::Const(sig_in.size());
 	if (arst) {
diff --git a/tests/proc/proc_mux_src.ys b/tests/proc/proc_mux_src.ys
index e25858e26..8c146db70 100644
--- a/tests/proc/proc_mux_src.ys
+++ b/tests/proc/proc_mux_src.ys
@@ -5,9 +5,9 @@ check -assert
 select -assert-count 2 tiny2/t:$eq
 select -assert-count 1 tiny2/t:$eq a:src=proc_mux_src.v:81.4-81.10 %i
 select -assert-count 1 tiny2/t:$eq a:src=proc_mux_src.v:84.4-84.10 %i
-# Flops cover the whole process
+# Flops cover the assigned to wire and whole process
 select -assert-count 1 tiny2/t:$dff
-select -assert-count 1 tiny2/t:$dff a:src=proc_mux_src.v:78.2-91.5 %i
+select -assert-count 1 tiny2/t:$dff a:src=proc_mux_src.v:76.19-76.22|proc_mux_src.v:78.2-91.5
 # Muxes are marked to the exact assignment statements they represent including the explicit default case
 select -assert-count 1 tiny2/t:$pmux
 select -assert-count 1 tiny2/t:$pmux a:src=proc_mux_src.v:80.5-80.13|proc_mux_src.v:83.5-83.15|proc_mux_src.v:86.5-86.15
@@ -18,8 +18,6 @@ select -assert-count 1 tiny/t:$mux
 select -assert-count 1 tiny/t:$mux a:proc_mux_src.v:65.5-65.13|proc_mux_src.v:63.3-67.10
 select -assert-count 0 tiny/t:$reduce_or
 
-dump nested
-#dump nested/t:$pmux
 # $reduce_or src covers the entire list of comparison RHSs
 # Each snippet is treated separately so it gets its own $eq and $reduce_or etc
 select -assert-count 3 nested/t:$reduce_or
@@ -30,4 +28,3 @@ select -assert-count 5 nested/t:$pmux
 select -assert-count 1 nested/t:$pmux a:src=proc_mux_src.v:21.5-21.20|proc_mux_src.v:26.5-26.20|proc_mux_src.v:32.5-45.12|proc_mux_src.v:48.5-48.19 %i
 # No nesting for output reg arith
 select -assert-count 1 nested/t:$pmux a:src=proc_mux_src.v:23.5-23.18|proc_mux_src.v:28.5-28.18|proc_mux_src.v:31.5-31.18|proc_mux_src.v:50.5-50.18 %i
-dump nested/t:$pmux