diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 6d41f42d6..a60053cf0 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -115,7 +115,10 @@ else()
         -fstack-clash-protection
     )
 
-    if (NOT CMAKE_BUILD_TYPE STREQUAL Debug)
+    # If we define _FORTIFY_SOURCE when it is already defined, compilation will fail
+    string(FIND "-D_FORTIFY_SOURCE" ${CMAKE_CXX_FLAGS} FORTIFY_SOURCE_DEFINED)
+
+    if (NOT CMAKE_BUILD_TYPE STREQUAL Debug AND NOT FORTIFY_SOURCE_DEFINED)
         # _FORTIFY_SOURCE can't be used without optimizations.
         add_compile_options(-U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2)
     endif()