diff --git a/CMakeLists.txt b/CMakeLists.txt
index 6c414bcbd4..fb18701a99 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -49,8 +49,6 @@ endif()
 
 if(WITH_STL)
   # Require at least C++17. C++20 is needed to avoid gsl::span
-  add_definitions(-DHAVE_CPP_STDLIB -DHAVE_GSL)
-
   if(CMAKE_MINOR_VERSION VERSION_GREATER "3.18")
     # Ask for 20, may get anything below
     set(CMAKE_CXX_STANDARD 20)
@@ -130,7 +128,7 @@ if(WITH_OTLP)
   set(protobuf_MODULE_COMPATIBLE ON)
   find_package(Protobuf)
   find_package(gRPC)
-  if((NOT protobuf_FOUND) OR (NOT gRPC_FOUND))
+  if((NOT Protobuf_FOUND AND NOT PROTOBUF_FOUND) OR (NOT gRPC_FOUND))
     if(WIN32 AND (NOT DEFINED CMAKE_TOOLCHAIN_FILE))
       install_windows_deps()
     endif()
@@ -142,7 +140,7 @@ if(WITH_OTLP)
       include(${CMAKE_TOOLCHAIN_FILE})
     endif()
 
-    if(NOT protobuf_FOUND)
+    if(NOT Protobuf_FOUND AND NOT PROTOBUF_FOUND)
       find_package(Protobuf REQUIRED)
     endif()
     if(NOT gRPC_FOUND)
@@ -157,7 +155,9 @@ if(WITH_OTLP)
       endif()
     endif()
     # Latest Protobuf uses mixed case instead of uppercase
-    set(PROTOBUF_PROTOC_EXECUTABLE ${Protobuf_PROTOC_EXECUTABLE})
+    if(Protobuf_PROTOC_EXECUTABLE)
+      set(PROTOBUF_PROTOC_EXECUTABLE ${Protobuf_PROTOC_EXECUTABLE})
+    endif()
   endif()
   message("PROTOBUF_PROTOC_EXECUTABLE=${PROTOBUF_PROTOC_EXECUTABLE}")
 
diff --git a/api/CMakeLists.txt b/api/CMakeLists.txt
index d9822530a2..1f1138cd1e 100644
--- a/api/CMakeLists.txt
+++ b/api/CMakeLists.txt
@@ -25,6 +25,8 @@ endif()
 
 if(WITH_STL)
   message("Building with standard library types...")
+  target_compile_definitions(opentelemetry_api INTERFACE HAVE_CPP_STDLIB
+                                                         HAVE_GSL)
 else()
   message("Building with nostd types...")
 endif()