diff --git a/src/rp2_common/boot_stage2/CMakeLists.txt b/src/rp2_common/boot_stage2/CMakeLists.txt
index 99adf40..73c3e3e 100644
--- a/src/rp2_common/boot_stage2/CMakeLists.txt
+++ b/src/rp2_common/boot_stage2/CMakeLists.txt
@@ -1,10 +1,13 @@
-# PICO_CMAKE_CONFIG: PICO_DEFAULT_BOOT_STAGE2_FILE, Default stage2 file to use unless overridden by pico_set_boot_stage2 on the TARGET; this setting is useful when explicitly setting the default build from a per board CMake file, group=build
-# PICO_CMAKE_CONFIG: PICO_DEFAULT_BOOT_STAGE2, Simpler alternative to specifying PICO_DEFAULT_BOOT_STAGE2_FILE where the file is src/boards/{PICO_DEFAULT_BOOT_STAGE2_FILE}.S, default=compile_time_choice, group=build
+# PICO_CMAKE_CONFIG: PICO_DEFAULT_BOOT_STAGE2_FILE, Default boot stage 2 file to use unless overridden by pico_set_boot_stage2 on the TARGET; this setting is useful when explicitly setting the default build from a per board CMake file, group=build
+# PICO_CMAKE_CONFIG: PICO_DEFAULT_BOOT_STAGE2, Simpler alternative to specifying PICO_DEFAULT_BOOT_STAGE2_FILE where the file is src/rp2_common/boot_stage2/{PICO_DEFAULT_BOOT_STAGE2}.S, default=compile_time_choice, group=build
+
 if (DEFINED ENV{PICO_DEFAULT_BOOT_STAGE2_FILE})
     set(PICO_DEFAULT_BOOT_STAGE2_FILE $ENV{PICO_DEFAULT_BOOT_STAGE2_FILE})
     message("Using PICO_DEFAULT_BOOT_STAGE2_FILE from environment ('${PICO_DEFAULT_BOOT_STAGE2_FILE}')")
+elif (PICO_DEFAULT_BOOT_STAGE2_FILE)
+    # explicitly set, so cache it
+    set(PICO_DEFAULT_BOOT_STAGE2_FILE "${PICO_DEFAULT_BOOT_STAGE2_FILE}" CACHE STRING "boot stage 2 source file" FORCE)
 endif()
-set(PICO_DEFAULT_BOOT_STAGE2_FILE "${PICO_DEFAULT_BOOT_STAGE2_FILE}" CACHE STRING "boot_stage2 source file" FORCE)
 
 set(PICO_BOOT_STAGE2_COMPILE_TIME_CHOICE_NAME compile_time_choice) # local var
 if (NOT PICO_DEFAULT_BOOT_STAGE2_FILE)
@@ -15,12 +18,12 @@ if (NOT PICO_DEFAULT_BOOT_STAGE2_FILE)
     if (NOT DEFINED PICO_DEFAULT_BOOT_STAGE2)
         set(PICO_DEFAULT_BOOT_STAGE2 ${PICO_BOOT_STAGE2_COMPILE_TIME_CHOICE_NAME})
     endif()
-    set(PICO_DEFAULT_BOOT_STAGE2 "${PICO_DEFAULT_BOOT_STAGE2}" CACHE STRING "boot_stage2 short name" FORCE)
+    set(PICO_DEFAULT_BOOT_STAGE2 "${PICO_DEFAULT_BOOT_STAGE2}" CACHE STRING "boot stage 2 short name" FORCE)
     set(PICO_DEFAULT_BOOT_STAGE2_FILE "${CMAKE_CURRENT_LIST_DIR}/${PICO_DEFAULT_BOOT_STAGE2}.S")
 endif()
 
 if (NOT EXISTS ${PICO_DEFAULT_BOOT_STAGE2_FILE})
-    message(FATAL_ERROR "Specified boot_stage2 source '${PICO_DEFAULT_BOOT_STAGE2_FILE}' does not exist.")
+    message(FATAL_ERROR "Specified boot stage 2 source '${PICO_DEFAULT_BOOT_STAGE2_FILE}' does not exist.")
 endif()
 
 # needed by function below
@@ -52,7 +55,7 @@ function(pico_define_boot_stage2 NAME SOURCES)
 
     pico_add_dis_output(${NAME})
     pico_add_map_output(${NAME})
-    
+
     set(ORIGINAL_BIN ${CMAKE_CURRENT_BINARY_DIR}/${NAME}.bin)
     set(PADDED_CHECKSUMMED_ASM ${CMAKE_CURRENT_BINARY_DIR}/${NAME}_padded_checksummed.S)
 
@@ -60,7 +63,7 @@ function(pico_define_boot_stage2 NAME SOURCES)
 
     add_custom_target(${NAME}_bin DEPENDS ${ORIGINAL_BIN})
     add_custom_command(OUTPUT ${ORIGINAL_BIN} DEPENDS ${NAME} COMMAND ${CMAKE_OBJCOPY} -Obinary $<TARGET_FILE:${NAME}> ${ORIGINAL_BIN})
-    
+
     add_custom_target(${NAME}_padded_checksummed_asm DEPENDS ${PADDED_CHECKSUMMED_ASM})
     add_custom_command(OUTPUT ${PADDED_CHECKSUMMED_ASM} DEPENDS ${ORIGINAL_BIN}
             COMMAND ${Python3_EXECUTABLE} ${PICO_BOOT_STAGE2_DIR}/pad_checksum -s 0xffffffff ${ORIGINAL_BIN} ${PADDED_CHECKSUMMED_ASM}
@@ -89,7 +92,7 @@ macro(pico_set_boot_stage2 TARGET NAME)
     if ("EXECUTABLE" STREQUAL "${target_type}")
         set_target_properties(${TARGET} PROPERTIES PICO_TARGET_BOOT_STAGE2 "${NAME}")
     else()
-        message(FATAL_ERROR "boot stage2 implementation must be set on executable not library")
+        message(FATAL_ERROR "boot stage 2 implementation must be set on executable not library")
     endif()
 endmacro()
 
diff --git a/src/rp2_common/boot_stage2/compile_time_choice.S b/src/rp2_common/boot_stage2/compile_time_choice.S
index cacb9aa..5aa2b96 100644
--- a/src/rp2_common/boot_stage2/compile_time_choice.S
+++ b/src/rp2_common/boot_stage2/compile_time_choice.S
@@ -11,19 +11,9 @@
 #include "boot_stage2/config.h"
 
 #ifdef PICO_BUILD_BOOT_STAGE2_NAME
-    // boot stage2 is configured by cmake, so use the name specified there
+    // boot stage 2 is configured by cmake, so use the name specified there
     #error PICO_BUILD_BOOT_STAGE2_NAME should not be defined for compile_time_choice builds
 #else
-    // boot stage2 is selected by board configu header, so we have to do some work
-    #if PICO_BOOT_STAGE2_CHOOSE_IS25LP080
-        #include "boot2_is25lp080.S"
-    #elif PICO_BOOT_STAGE2_CHOOSE_W25Q080
-        #include "boot2_w28q080.S"
-    #elif PICO_BOOT_STAGE2_CHOOSE_W25X10CL
-        #include "boot2_w25x10cl.S"
-    #elif PICO_BOOT_STAGE2_CHOOSE_GENERIC_03H
-        #include "boot2_generic_03h.S"
-    #else
-        #error unknown boot stage2 choice
-    #endif
+    // boot stage 2 is selected by board config header, and PICO_BOOT_STAGE2_ASM is set in boot_stage2/config.h
+    #include PICO_BOOT_STAGE2_ASM
 #endif
diff --git a/src/rp2_common/boot_stage2/include/boot_stage2/config.h b/src/rp2_common/boot_stage2/include/boot_stage2/config.h
index f6fdb9f..a8179b9 100644
--- a/src/rp2_common/boot_stage2/include/boot_stage2/config.h
+++ b/src/rp2_common/boot_stage2/include/boot_stage2/config.h
@@ -9,30 +9,74 @@
 
 // NOTE THIS HEADER IS INCLUDED FROM ASSEMBLY
 
+#include "pico/config.h"
+
 // PICO_CONFIG: PICO_BUILD_BOOT_STAGE2_NAME, The name of the boot stage 2 if selected by the build, group=boot_stage2
-// PICO_CONFIG: PICO_BOOT_STAGE2_CHOOSE_IS25LP080, Select boot2_is25lp080 as the boot stage 2 when no boot stage2 selection is made by the CMake build, type=bool, default=false, group=boot_stage2
-// PICO_CONFIG: PICO_BOOT_STAGE2_CHOOSE_W25Q080, Select boot2_w28q080 as the boot stage 2 when no boot stage2 selection is made by the CMake build, type=bool, default=false, group=boot_stage2
-// PICO_CONFIG: PICO_BOOT_STAGE2_CHOOSE_W25X10CL, Select boot2_is25lp080 as the boot stage 2 when no boot stage2 selection is made by the CMake build, type=bool, default=false, group=boot_stage2
-// PICO_CONFIG: PICO_BOOT_STAGE2_CHOOSE_GENERIC_03H, Select boot2_generic_03h as the boot stage 2 when no boot stage2 selection is made by the CMake build, type=bool, default=true, group=boot_stage2
+#ifdef PICO_BUILD_BOOT_STAGE2_NAME
+    #define _BOOT_STAGE2_SELECTED
+#else
+    // check that multiple boot stage 2 options haven't been set...
+
+// PICO_CONFIG: PICO_BOOT_STAGE2_CHOOSE_IS25LP080, Select boot2_is25lp080 as the boot stage 2 when no boot stage 2 selection is made by the CMake build, type=bool, default=0, group=boot_stage2
+#ifndef PICO_BOOT_STAGE2_CHOOSE_IS25LP080
+    #define PICO_BOOT_STAGE2_CHOOSE_IS25LP080 0
+#elif PICO_BOOT_STAGE2_CHOOSE_IS25LP080
+    #ifdef _BOOT_STAGE2_SELECTED
+        #error multiple boot stage 2 options chosen
+    #endif
+    #define _BOOT_STAGE2_SELECTED
+#endif
+// PICO_CONFIG: PICO_BOOT_STAGE2_CHOOSE_W25Q080, Select boot2_w25q080 as the boot stage 2 when no boot stage 2 selection is made by the CMake build, type=bool, default=0, group=boot_stage2
+#ifndef PICO_BOOT_STAGE2_CHOOSE_W25Q080
+    #define PICO_BOOT_STAGE2_CHOOSE_W25Q080 0
+#elif PICO_BOOT_STAGE2_CHOOSE_W25Q080
+    #ifdef _BOOT_STAGE2_SELECTED
+        #error multiple boot stage 2 options chosen
+    #endif
+    #define _BOOT_STAGE2_SELECTED
+#endif
+// PICO_CONFIG: PICO_BOOT_STAGE2_CHOOSE_W25X10CL, Select boot2_w25x10cl as the boot stage 2 when no boot stage 2 selection is made by the CMake build, type=bool, default=0, group=boot_stage2
+#ifndef PICO_BOOT_STAGE2_CHOOSE_W25X10CL
+    #define PICO_BOOT_STAGE2_CHOOSE_W25X10CL 0
+#elif PICO_BOOT_STAGE2_CHOOSE_W25X10CL
+    #ifdef _BOOT_STAGE2_SELECTED
+        #error multiple boot stage 2 options chosen
+    #endif
+    #define _BOOT_STAGE2_SELECTED
+#endif
+// PICO_CONFIG: PICO_BOOT_STAGE2_CHOOSE_GENERIC_03H, Select boot2_generic_03h as the boot stage 2 when no boot stage 2 selection is made by the CMake build, type=bool, default=1, group=boot_stage2
+#if defined(PICO_BOOT_STAGE2_CHOOSE_GENERIC_03H) && PICO_BOOT_STAGE2_CHOOSE_GENERIC_03H
+    #ifdef _BOOT_STAGE2_SELECTED
+        #error multiple boot stage 2 options chosen
+    #endif
+    #define _BOOT_STAGE2_SELECTED
+#endif
+
+#endif // PICO_BUILD_BOOT_STAGE2_NAME
 
 #ifdef PICO_BUILD_BOOT_STAGE2_NAME
-    // boot stage2 is configured by cmake, so use the name specified there
+    // boot stage 2 is configured by cmake, so use the name specified there
     #define PICO_BOOT_STAGE2_NAME PICO_BUILD_BOOT_STAGE2_NAME
 #else
-    // boot stage2 is selected by board configu header, so we have to do some work
-    // NOTE: this switch is mirrored in compile_time_choice.S
+    // boot stage 2 is selected by board config header, so we have to do some work
     #if PICO_BOOT_STAGE2_CHOOSE_IS25LP080
-        #define PICO_BOOT_STAGE2_NAME "boot2_is25lp080"
+        #define _BOOT_STAGE2 boot2_is25lp080
     #elif PICO_BOOT_STAGE2_CHOOSE_W25Q080
-        #define PICO_BOOT_STAGE2_NAME "boot2_w28q080"
+        #define _BOOT_STAGE2 boot2_w25q080
     #elif PICO_BOOT_STAGE2_CHOOSE_W25X10CL
-        #define PICO_BOOT_STAGE2_NAME "boot2_w25x10cl"
-    #elif PICO_BOOT_STAGE2_CHOOSE_GENERIC_03H || !defined(PICO_BOOT_STAGE2_CHOOSE_GENERIC_03H)
+        #define _BOOT_STAGE2 boot2_w25x10cl
+    #elif !defined(PICO_BOOT_STAGE2_CHOOSE_GENERIC_03H) || PICO_BOOT_STAGE2_CHOOSE_GENERIC_03H
         #undef PICO_BOOT_STAGE2_CHOOSE_GENERIC_03H
         #define PICO_BOOT_STAGE2_CHOOSE_GENERIC_03H 1
-        #define PICO_BOOT_STAGE2_NAME "boot2_generic_03h"
+        #define _BOOT_STAGE2 boot2_generic_03h
     #else
-        #error no bootstage2 is defined by PICO_BOOT_STAGE2_CHOOSE_ macro
+        #error no boot stage 2 is defined by PICO_BOOT_STAGE2_CHOOSE_ macro
     #endif
+    // we can't include cdefs in assembly, so define our own, but avoid conflict with real ones for c inclusion
+    #define _PICO__STRING(x) #x
+    #define _PICO__XSTRING(x) _PICO__STRING(x)
+    #define _PICO__CONCAT1(x, y) x ## y
+    #define PICO_BOOT_STAGE2_NAME _PICO__XSTRING(_BOOT_STAGE2)
+    #define PICO_BOOT_STAGE2_ASM _PICO__XSTRING(_PICO__CONCAT1(_BOOT_STAGE2,.S))
+#endif
 #endif
-#endif
\ No newline at end of file
diff --git a/src/rp2_common/pico_standard_link/binary_info.c b/src/rp2_common/pico_standard_link/binary_info.c
index bde2027..aa67ac4 100644
--- a/src/rp2_common/pico_standard_link/binary_info.c
+++ b/src/rp2_common/pico_standard_link/binary_info.c
@@ -6,7 +6,10 @@
 
 #if !PICO_NO_BINARY_INFO && !PICO_NO_PROGRAM_INFO
 #include "pico/binary_info.h"
+
+#if !PICO_NO_FLASH
 #include "boot_stage2/config.h"
+#endif
 
 // Note we put at most 4 pieces of binary info in the reset section because that's how much spare space we had
 // (picked the most common ones)... if there is a link failure because of .reset section overflow then move
@@ -89,4 +92,4 @@ bi_decl(bi_program_build_attribute("All optimization disabled"))
 #endif
 #endif
 
-#endif
\ No newline at end of file
+#endif