diff --git a/src/rp2_common/pico_double/double_init_rom.c b/src/rp2_common/pico_double/double_init_rom.c
index 1a25559..2255939 100644
--- a/src/rp2_common/pico_double/double_init_rom.c
+++ b/src/rp2_common/pico_double/double_init_rom.c
@@ -19,6 +19,8 @@ static __attribute__((noreturn)) void missing_double_func_shim(void) {
 #endif
 extern void double_table_shim_on_use_helper(void);
 
+void __attribute__((weak)) *sf_clz_func;
+
 void __aeabi_double_init(void) {
     int rom_version = rp2040_rom_version();
 #if PICO_DOUBLE_SUPPORT_ROM_V1
@@ -63,4 +65,6 @@ void __aeabi_double_init(void) {
         // we use the unused entry for SINCOS
         sd_table[SF_TABLE_V3_FSINCOS / 4] = (uintptr_t) double_table_shim_on_use_helper;
     }
+
+    sf_clz_func = rom_func_lookup(rom_table_code('L', '3'));
 }
diff --git a/src/rp2_common/pico_float/float_init_rom.c b/src/rp2_common/pico_float/float_init_rom.c
index 24c74ce..c7a52c2 100644
--- a/src/rp2_common/pico_float/float_init_rom.c
+++ b/src/rp2_common/pico_float/float_init_rom.c
@@ -11,7 +11,7 @@
 // NOTE THIS FUNCTION TABLE IS NOT PUBLIC OR NECESSARILY COMPLETE...
 // IT IS ***NOT*** SAFE TO CALL THESE FUNCTION POINTERS FROM ARBITRARY CODE
 uint32_t sf_table[SF_TABLE_V2_SIZE / 2];
-void *sf_clz_func;
+void __attribute__((weak)) *sf_clz_func;
 
 #if !PICO_FLOAT_SUPPORT_ROM_V1
 static __attribute__((noreturn)) void missing_float_func_shim(void) {