diff --git a/CMakeLists.txt b/CMakeLists.txt
index df297e0cb7..b7aaf202fa 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -249,11 +249,14 @@ if(UNIX)
     set(CMAKE_REQUIRED_DEFINITIONS "-D_LARGEFILE_SOURCE" "-D_LARGEFILE64_SOURCE")
     # Use readdir64 if available.
     check_symbol_exists(readdir64 "dirent.h" REALM_HAVE_READDIR64)
-    cmake_reset_check_state()
-    set(CMAKE_REQUIRED_DEFINITIONS "-D_POSIX_C_SOURCE=200112L")
-    check_symbol_exists(posix_fallocate "fcntl.h" REALM_HAVE_POSIX_FALLOCATE)
-    if(REALM_HAVE_POSIX_FALLOCATE)
-        add_compile_definitions("_POSIX_C_SOURCE=200112L")
+
+    if(NOT ANDROID)
+        cmake_reset_check_state()
+        set(CMAKE_REQUIRED_DEFINITIONS "-D_POSIX_C_SOURCE=200112L")
+        check_symbol_exists(posix_fallocate "fcntl.h" REALM_HAVE_POSIX_FALLOCATE)
+        if(REALM_HAVE_POSIX_FALLOCATE)
+            add_compile_definitions("_POSIX_C_SOURCE=200112L")
+        endif()
     endif()
     cmake_pop_check_state()
 endif()