diff --git a/cmake/protobuf-config.cmake.in b/cmake/protobuf-config.cmake.in
index 3e730f2de3..11b85d3c07 100644
--- a/cmake/protobuf-config.cmake.in
+++ b/cmake/protobuf-config.cmake.in
@@ -81,8 +81,6 @@ function(protobuf_generate)
           list(APPEND _protobuf_include_path -I ${_abs_path})
       endif()
     endforeach()
-  else()
-    set(_protobuf_include_path -I ${CMAKE_CURRENT_SOURCE_DIR})
   endif()
 
   foreach(DIR ${protobuf_generate_IMPORT_DIRS})
@@ -93,12 +91,31 @@ function(protobuf_generate)
     endif()
   endforeach()
 
+  if(NOT _protobuf_include_path)
+    set(_protobuf_include_path -I ${CMAKE_CURRENT_SOURCE_DIR})
+  endif()
+
   set(_generated_srcs_all)
   foreach(_proto ${protobuf_generate_PROTOS})
     get_filename_component(_abs_file ${_proto} ABSOLUTE)
     get_filename_component(_abs_dir ${_abs_file} DIRECTORY)
     get_filename_component(_basename ${_proto} NAME_WLE)
-    file(RELATIVE_PATH _rel_dir ${CMAKE_CURRENT_SOURCE_DIR} ${_abs_dir})
+
+    set(_suitable_include_found FALSE)
+    foreach(DIR ${_protobuf_include_path})
+      if(NOT DIR STREQUAL "-I")
+        file(RELATIVE_PATH _rel_dir ${DIR} ${_abs_dir})
+        if(NOT "${_rel_dir}" MATCHES "^\.\.[/\\].*")
+          set(_suitable_include_found TRUE)
+          break()
+        endif()
+      endif()
+    endforeach()
+
+    if(NOT _suitable_include_found)
+      message(SEND_ERROR "Error: protobuf_generate could not find any correct proto include directory.")
+      return()
+    endif()
 
     set(_generated_srcs)
     foreach(_ext ${protobuf_generate_GENERATE_EXTENSIONS})