diff --git a/boot/bootutil/src/encrypted.c b/boot/bootutil/src/encrypted.c
index 13ba2f4..6ac10d6 100644
--- a/boot/bootutil/src/encrypted.c
+++ b/boot/bootutil/src/encrypted.c
@@ -306,7 +306,7 @@
     return rc;
 }
 
-int
+bool
 boot_enc_valid(const struct flash_area *fap)
 {
     int rc;
@@ -315,7 +315,7 @@
     if (rc < 0) {
         /* can't get proper slot number - skip encryption, */
         /* postpone the erro for a upper layer */
-        return 0;
+        return false;
     }
 
     return enc_state[rc].valid;