diff --git a/toolchain_GNUARM.cmake b/toolchain_GNUARM.cmake
index ee31875..e47668e 100644
--- a/toolchain_GNUARM.cmake
+++ b/toolchain_GNUARM.cmake
@@ -75,18 +75,24 @@
 
 macro(tfm_toolchain_set_processor_arch)
     if (DEFINED TFM_SYSTEM_PROCESSOR)
-        set(CMAKE_SYSTEM_PROCESSOR ${TFM_SYSTEM_PROCESSOR})
+        if(TFM_SYSTEM_PROCESSOR MATCHES "cortex-m85")
+            # GNUARM does not support the -mcpu=cortex-m85 flag yet
+            # TODO: Remove this exception when the cortex-m85 support comes out.
+            message(WARNING "Cortex-m85 is not supported by GCC. Falling back to -march usage.")
+        else()
+            set(CMAKE_SYSTEM_PROCESSOR ${TFM_SYSTEM_PROCESSOR})
 
-        if (DEFINED TFM_SYSTEM_DSP)
-            if (NOT TFM_SYSTEM_DSP)
-                string(APPEND CMAKE_SYSTEM_PROCESSOR "+nodsp")
+            if (DEFINED TFM_SYSTEM_DSP)
+                if (NOT TFM_SYSTEM_DSP)
+                    string(APPEND CMAKE_SYSTEM_PROCESSOR "+nodsp")
+                endif()
             endif()
-        endif()
-        if(GCC_VERSION VERSION_GREATER_EQUAL "8.0.0")
-            if (DEFINED CONFIG_TFM_FP)
-                if(CONFIG_TFM_FP STREQUAL "0" AND
-                   NOT TFM_SYSTEM_ARCHITECTURE STREQUAL "armv6-m")
-                    string(APPEND CMAKE_SYSTEM_PROCESSOR "+nofp")
+            if(GCC_VERSION VERSION_GREATER_EQUAL "8.0.0")
+                if (DEFINED CONFIG_TFM_FP)
+                    if(CONFIG_TFM_FP STREQUAL "0" AND
+                        NOT TFM_SYSTEM_ARCHITECTURE STREQUAL "armv6-m")
+                            string(APPEND CMAKE_SYSTEM_PROCESSOR "+nofp")
+                    endif()
                 endif()
             endif()
         endif()
@@ -140,7 +146,7 @@
     unset(CMAKE_C_FLAGS_INIT)
     unset(CMAKE_ASM_FLAGS_INIT)
 
-    if (DEFINED TFM_SYSTEM_PROCESSOR)
+    if (CMAKE_SYSTEM_PROCESSOR)
         set(CMAKE_C_FLAGS_INIT "-mcpu=${CMAKE_SYSTEM_PROCESSOR}")
         set(CMAKE_ASM_FLAGS_INIT "-mcpu=${CMAKE_SYSTEM_PROCESSOR}")
         set(CMAKE_C_LINK_FLAGS "-mcpu=${CMAKE_SYSTEM_PROCESSOR}")