diff --git a/tools/build-gh.sh b/tools/build-gh.sh
index 34a008617..208bec592 100755
--- a/tools/build-gh.sh
+++ b/tools/build-gh.sh
@@ -70,7 +70,7 @@ fi
 : "${COMMON_OPTIONS:="-DCMAKE_BUILD_TYPE=$BUILD_TYPE -DCMAKE_RULE_MESSAGES=OFF -Wno-dev "}"
 : "${EXTRA_OPTIONS:="$EXTRA_OPTIONS"}"
 
-COMMON_OPTIONS+=${EXTRA_OPTIONS}
+COMMON_OPTIONS+=${EXTRA_OPTIONS}" "
 
 : "${FIRMARE_TARGET:="firmware-size"}"
 
@@ -173,6 +173,10 @@ do
         commando8)
             BUILD_OPTIONS+="-DPCB=X7 -DPCBREV=COMMANDO8"
             ;;
+        *)
+            echo "Unknown target: $target_name"
+            exit 1
+            ;;
     esac
 
     cmake ${BUILD_OPTIONS} "${SRCDIR}"