diff --git a/examples/ecp5_evn/Makefile b/examples/ecp5_evn/Makefile
index 51f1a6f..40622b0 100644
--- a/examples/ecp5_evn/Makefile
+++ b/examples/ecp5_evn/Makefile
@@ -1,5 +1,5 @@
 PROJ=blinky
-TRELLIS=/usr/share/trellis
+TRELLIS?=/usr/share/trellis
 
 all: ${PROJ}.bit
 
diff --git a/examples/picorv32_versa5g/Makefile b/examples/picorv32_versa5g/Makefile
index 973c4f5..c259c04 100644
--- a/examples/picorv32_versa5g/Makefile
+++ b/examples/picorv32_versa5g/Makefile
@@ -1,4 +1,4 @@
-TRELLIS=/usr/share/trellis
+TRELLIS?=/usr/share/trellis
 
 firmware.elf: sections.lds firmware.s
 	riscv32-unknown-elf-gcc -march=rv32i -Wl,-Bstatic,-T,sections.lds,--strip-debug -ffreestanding -nostdlib -o firmware.elf firmware.s
diff --git a/examples/soc_ecp5_evn/Makefile b/examples/soc_ecp5_evn/Makefile
index 4d8093b..dd916be 100644
--- a/examples/soc_ecp5_evn/Makefile
+++ b/examples/soc_ecp5_evn/Makefile
@@ -1,4 +1,4 @@
-TRELLIS=/usr/share/trellis
+TRELLIS?=/usr/share/trellis
 
 firmware.elf: sections.lds start.s firmware.c
 	riscv32-unknown-elf-gcc -march=rv32i -Wl,-Bstatic,-T,sections.lds,--strip-debug -ffreestanding -nostdlib -o firmware.elf start.s firmware.c
diff --git a/examples/soc_versa5g/Makefile b/examples/soc_versa5g/Makefile
index fb3c197..4f8c9e3 100644
--- a/examples/soc_versa5g/Makefile
+++ b/examples/soc_versa5g/Makefile
@@ -1,4 +1,4 @@
-TRELLIS=/usr/share/trellis
+TRELLIS?=/usr/share/trellis
 
 firmware.elf: sections.lds start.s firmware.c
 	riscv32-unknown-elf-gcc -march=rv32i -Wl,-Bstatic,-T,sections.lds,--strip-debug -ffreestanding -nostdlib -o firmware.elf start.s firmware.c
diff --git a/examples/versa5g/Makefile b/examples/versa5g/Makefile
index 811295c..a540232 100644
--- a/examples/versa5g/Makefile
+++ b/examples/versa5g/Makefile
@@ -1,6 +1,6 @@
 PROJ=demo
 CONSTR=versa.lpf
-TRELLIS=/usr/share/trellis
+TRELLIS?=/usr/share/trellis
 
 all: ${PROJ}.bit