diff --git a/common.sh b/common.sh
index 56434b2..c71b11b 100755
--- a/common.sh
+++ b/common.sh
@@ -76,7 +76,7 @@ function error_exit() {
 }
 
 function check_binary() {
-  if command -v "$1" >/dev/null 2>&1; then
+  if !command -v "$1" >/dev/null 2>&1; then
     error_exit "failed to find required binary: $1"
   fi
 }