diff --git a/build/build.sh b/build/build.sh
index 93dc54d98b130f29ee659ceae3e37f1f12ff6152..1d42e769e31c1bd06cc091921cd8bde6a1a03d1d 100644
--- a/build/build.sh
+++ b/build/build.sh
@@ -38,7 +38,7 @@ if ! dpkg -s gawk > /dev/null; then
 fi
 echo "Detected gawk..."
 echo "Checking for unzip..."
-if dpkg -s unzip > /dev/null; then
+if ! dpkg -s unzip > /dev/null; then
   echo "unzip is not installed"
   exit 1
 fi