diff --git a/GNUmakefile b/GNUmakefile
index aea9ccedc1ad1e051d13f21ec20ba0b928494c73..e5036285bcd94b8170868a9e788df33d9c8b1b0c 100644
--- a/GNUmakefile
+++ b/GNUmakefile
@@ -48,7 +48,7 @@ sql: fe-sqlite
 
 BLOSC_CPPFLAGS := \
 	-Ithirdparty/blosc \
-	-DHAVE_LZ4 -DHAVE_SNAPPY -DHAVE_ZLIB -DHAVE_ZSTD \
+	-DHAVE_LZ4 -DHAVE_SNAPPY -DHAVE_ZLIB -DHAVE_ZSTD -DHAVE_UNISTD_H \
 	-Ithirdparty/blosc/internal-complibs/zlib-1.2.8 \
 	-Ithirdparty/blosc/internal-complibs/lz4-1.7.2 \
 	-Ithirdparty/blosc/internal-complibs/snappy-1.1.1 \