diff --git a/src/rp2_common/pico_clib_interface/CMakeLists.txt b/src/rp2_common/pico_clib_interface/CMakeLists.txt
index 84d3faf62..5fae421e7 100644
--- a/src/rp2_common/pico_clib_interface/CMakeLists.txt
+++ b/src/rp2_common/pico_clib_interface/CMakeLists.txt
@@ -36,8 +36,43 @@ if (NOT TARGET pico_clib_interface)
 
     if (NOT PICO_CLIB)
         # PICO_CMAKE_CONFIG: PICO_CLIB, The C library to use e.g. newlib/picolibc/llvm_libc, type=string, default=based on PICO_COMPILER, group=build, docref=cmake-toolchain-config
-        set(PICO_CLIB newlib)
-    endif()
+        set(CLIB_DETECT_CODE "
+            #include <stdio.h>
+            #ifdef __PICOLIBC__
+            #define USING_PICOLIBC 1
+            #elif defined(__NEWLIB__)
+            #define USING_NEWLIB 1
+            #endif
+            
+            #if (picolibc && !USING_PICOLIBC) || (newlib && !USING_NEWLIB)
+            #error not using wanted c library
+            #endif
+        ")
+
+        # Create a temporary file for the source
+        set(CLIB_DETECT_SOURCE "${CMAKE_CURRENT_BINARY_DIR}/clib_check.c")
+        file(WRITE "${CLIB_DETECT_SOURCE}" "${CLIB_DETECT_CODE}")
 
+        set(CMAKE_TRY_COMPILE_TARGET_TYPE STATIC_LIBRARY)
+        foreach(CLIB newlib picolibc)
+            # Attempt to compile the source file
+            try_compile(CLIB_MATCHED
+                    "${CMAKE_CURRENT_BINARY_DIR}"              # Directory for temporary build files
+                    "${CLIB_DETECT_SOURCE}"                    # Source file to compile
+                    COMPILE_DEFINITIONS "-D${CLIB}=1"
+            )
+            if (CLIB_MATCHED)
+                set(PICO_CLIB ${CLIB})
+                break()
+            endif()
+        endforeach ()
+        if (NOT PICO_CLIB)
+            message("C library not detected; defaulting to newlib")
+            set(PICO_CLIB newlib)
+        endif()
+        file(REMOVE "${CLIB_DETECT_SOURCE}")
+        set(PICO_CLIB "${PICO_CLIB}" CACHE INTERNAL "")
+    endif()
+    message("C library type is ${PICO_CLIB}")
     target_link_libraries(pico_clib_interface INTERFACE pico_${PICO_CLIB}_interface)
 endif()