diff --git a/External/FreeSASA/CMakeLists.txt b/External/FreeSASA/CMakeLists.txt
index 43dfbdc40..880231b01 100644
--- a/External/FreeSASA/CMakeLists.txt
+++ b/External/FreeSASA/CMakeLists.txt
@@ -67,9 +67,11 @@ endif()
 
 set (freesasa_h ${FREESASA_SRC_DIR}/src/freesasa.h)
 file(READ ${freesasa_h} freesasa_h_data)
-string(REGEX REPLACE "(#include <stdio.h>)" "\\1\n#include <RDGeneral/export.h>" freesasa_h_data "${freesasa_h_data}")
-string(REGEX REPLACE "([^R][^D][^K][^I][^T][^_][^F][^R][^E][^E][^S][^A][^S][^A][^_][^C][^L][^I][^B][^_][^E][^X][^P][^O][^R][^T][^ ])(extern const)" "\\1RDKIT_FREESASA_CLIB_EXPORT \\2" freesasa_h_data "${freesasa_h_data}")
-file(WRITE ${freesasa_h} "${freesasa_h_data}")
+if (NOT freesasa_h_data MATCHES "RDGeneral/export")
+  string(REGEX REPLACE "(#include <stdio.h>)" "\\1\n#include <RDGeneral/export.h>" freesasa_h_data "${freesasa_h_data}")
+  string(REGEX REPLACE "([^R][^D][^K][^I][^T][^_][^F][^R][^E][^E][^S][^A][^S][^A][^_][^C][^L][^I][^B][^_][^E][^X][^P][^O][^R][^T][^ ])(extern const)" "\\1RDKIT_FREESASA_CLIB_EXPORT \\2" freesasa_h_data "${freesasa_h_data}")
+  file(WRITE ${freesasa_h} "${freesasa_h_data}")
+endif()
 
 add_definitions(-DUSE_THREADS=0)
 add_definitions(-DUSE_JSON=0)