diff --git a/external/panphasia_ho/PAN_FFTW3.h b/external/panphasia_ho/PAN_FFTW3.h
index 1f30ddf..3f53182 100644
--- a/external/panphasia_ho/PAN_FFTW3.h
+++ b/external/panphasia_ho/PAN_FFTW3.h
@@ -2,6 +2,8 @@
 // between single/double precision FTs
 
 // include CMake controlled configuration settings
+#pragma once
+#include "cmake_config.hh"
 
 #if defined(USE_PRECISION_DOUBLE)
 #define FOURIER_DOUBLE
diff --git a/include/cmake_config.hh.in b/include/cmake_config.hh.in
index 03768a3..cc0da5e 100644
--- a/include/cmake_config.hh.in
+++ b/include/cmake_config.hh.in
@@ -1,8 +1,10 @@
 #pragma once
 
-constexpr char CMAKE_BUILDTYPE_STR[] = "${CMAKE_BUILD_TYPE}";
 
 #define USE_PRECISION_${CODE_PRECISION}
+
+#ifdef __cplusplus
+constexpr char CMAKE_BUILDTYPE_STR[] = "${CMAKE_BUILD_TYPE}";
 #if defined(USE_PRECISION_FLOAT)
   constexpr char CMAKE_PRECISION_STR[] = "single";
 #elif defined(USE_PRECISION_DOUBLE)
@@ -31,4 +33,6 @@ extern "C"
   extern const char *GIT_TAG;
   extern const char *GIT_REV;
   extern const char *GIT_BRANCH;
-}
\ No newline at end of file
+
+}
+#endif // __cplusplus
\ No newline at end of file