diff --git a/cmake/dependencies/AMReX.cmake b/cmake/dependencies/AMReX.cmake
index 14990aaf..d6adc64a 100644
--- a/cmake/dependencies/AMReX.cmake
+++ b/cmake/dependencies/AMReX.cmake
@@ -4,6 +4,9 @@ macro(find_amrex)
     elseif(pyAMReX_amrex_src)
         message(STATUS "Compiling local AMReX ...")
         message(STATUS "AMReX source path: ${pyAMReX_amrex_src}")
+        if(NOT IS_DIRECTORY ${pyAMReX_amrex_src})
+            message(FATAL_ERROR "Specified directory pyAMReX_amrex_src='${pyAMReX_amrex_src}' does not exist!")
+        endif()
     elseif(pyAMReX_amrex_internal)
         message(STATUS "Downloading AMReX ...")
         message(STATUS "AMReX repository: ${pyAMReX_amrex_repo} (${pyAMReX_amrex_branch})")
diff --git a/cmake/dependencies/pybind11.cmake b/cmake/dependencies/pybind11.cmake
index 626f5e66..bee122e5 100644
--- a/cmake/dependencies/pybind11.cmake
+++ b/cmake/dependencies/pybind11.cmake
@@ -4,6 +4,9 @@ function(find_pybind11)
     elseif(pyAMReX_pybind11_src)
         message(STATUS "Compiling local pybind11 ...")
         message(STATUS "pybind11 source path: ${pyAMReX_pybind11_src}")
+        if(NOT IS_DIRECTORY ${pyAMReX_pybind11_src})
+            message(FATAL_ERROR "Specified directory pyAMReX_pybind11_src='${pyAMReX_pybind11_src}' does not exist!")
+        endif()
     elseif(pyAMReX_pybind11_internal)
         message(STATUS "Downloading pybind11 ...")
         message(STATUS "pybind11 repository: ${pyAMReX_pybind11_repo} (${pyAMReX_pybind11_branch})")