diff --git a/soc/openisa/rv32m1/CMakeLists.txt b/soc/openisa/rv32m1/CMakeLists.txt
index cd65ea9d628..fcfda5f17ed 100644
--- a/soc/openisa/rv32m1/CMakeLists.txt
+++ b/soc/openisa/rv32m1/CMakeLists.txt
@@ -2,14 +2,10 @@
 #
 # SPDX-License-Identifier: Apache-2.0
 
-if(CONFIG_SOC_OPENISA_RV32M1_RI5CY)
-  if (CONFIG_RISCV_GENERIC_TOOLCHAIN)
-    zephyr_compile_options(-march=rv32imc_zicsr_zifencei)
-  else()
-    zephyr_compile_options(-march=rv32imcxpulpv2)
-  endif()
-elseif(CONFIG_SOC_OPENISA_RV32M1_ZERO_RISCY)
-  zephyr_compile_options(-march=rv32imc_zicsr_zifencei)
+# Let's rely on `-march` being generated by the CMake script based on which `CONFIG_RISCV_ISA_EXT_*`
+# options are y-selected; provide full arch string with the custom extension otherwise.
+if(CONFIG_SOC_OPENISA_RV32M1_RI5CY AND NOT CONFIG_RISCV_GENERIC_TOOLCHAIN)
+  zephyr_compile_options(-march=rv32imcxpulpv2)
 endif()
 
 zephyr_sources(