diff --git a/pkgs/development/libraries/pcre/default.nix b/pkgs/development/libraries/pcre/default.nix
index 141c06f00b8..ccef9d08f73 100644
--- a/pkgs/development/libraries/pcre/default.nix
+++ b/pkgs/development/libraries/pcre/default.nix
@@ -13,7 +13,7 @@ stdenv.mkDerivation {
   # problem. In case we ever update the Darwin GCC version, the exception for
   # that platform ought to be removed.
   configureFlags = ''
-    CPPFLAGS=-NDEBUG CFLAGS=-O3 CXXFLAGS=${if stdenv.isDarwin then "-O0" else "-O3"}
+    CPPFLAGS=-DNDEBUG CFLAGS=-O3 CXXFLAGS=${if stdenv.isDarwin then "-O0" else "-O3"}
     ${if unicodeSupport then "--enable-unicode-properties" else ""}
     ${if !cplusplusSupport then "--disable-cpp" else ""}
   '';