diff --git a/verilog_iverilog/clock/Makefile b/verilog_iverilog/clock/Makefile
index d56fca0..3d3b6e1 100644
--- a/verilog_iverilog/clock/Makefile
+++ b/verilog_iverilog/clock/Makefile
@@ -1,18 +1,18 @@
 SOURCES=clock.v clock-tb.v
-VPP=clock.vpp
+VVP=clock.vvp
 
 .PHONY: run
-run: ${VPP}
-	vvp ${VPP}
+run: ${VVP}
+	vvp ${VVP}
 
 .PHONY: wave
-wave: ${VPP}
-	vvp ${VPP} -lxt2
+wave: ${VVP}
+	vvp ${VVP} -lxt2
 	gtkwave test.lx2 gtkwave_savefile.gtkw
 
-${VPP} : ${SOURCES}
+${VVP} : ${SOURCES}
 	iverilog -g2012 $^ -o $@
 
 .PHONY: clean
 clean:
-	rm -f ${VPP} test.lx2
+	rm -f ${VVP} test.lx2
diff --git a/verilog_iverilog/multiplexer/Makefile b/verilog_iverilog/multiplexer/Makefile
index f79db3e..49c7f82 100644
--- a/verilog_iverilog/multiplexer/Makefile
+++ b/verilog_iverilog/multiplexer/Makefile
@@ -1,11 +1,11 @@
 SOURCES=multiplexer.v multiplexer-tb.v
-VPP=multiplexer.vpp
+VVP=multiplexer.vvp
 
-run: ${VPP}
-	vvp ${VPP}
+run: ${VVP}
+	vvp ${VVP}
 
-${VPP} : ${SOURCES}
+${VVP} : ${SOURCES}
 	iverilog $^ -o $@
 
 clean:
-	rm -f ${VPP}
+	rm -f ${VVP}