diff --git a/scripts/prebuild.sh b/scripts/prebuild.sh
index 2dd9a095..3c25587e 100755
--- a/scripts/prebuild.sh
+++ b/scripts/prebuild.sh
@@ -41,13 +41,13 @@ if [[ "$paths_source" != "true" ]]; then
     exit 1
 fi
 
-if [ -d "$ANDROID_HOME" ]; then
-  echo "\$ANDROID_HOME does exist."
+if [ ! -d "$ANDROID_HOME" ]; then
+  echo "\$ANDROID_HOME does not exist."
   exit 1
 fi
 
-if [ -d "$ANDROID_NDK" ]; then
-  echo "\$ANDROID_NDK does exist."
+if [ ! -d "$ANDROID_NDK" ]; then
+  echo "\$ANDROID_NDK does not exist."
   exit 1
 fi