diff --git a/utils/pdfsig.cc b/utils/pdfsig.cc
index 6762c37..895876f 100644
--- a/utils/pdfsig.cc
+++ b/utils/pdfsig.cc
@@ -154,7 +154,7 @@
 
   for (unsigned int i = 0; i < sigCount; i++) {
     sig_info = sig_widgets.at(i)->validateSignature(!dontVerifyCert, false);
-    printf("Signature #%d:\n", i+1);
+    printf("Signature #%u:\n", i+1);
     printf("  - Signer Certificate Common Name: %s\n", sig_info->getSignerName());
     printf("  - Signing Time: %s\n", time_str = getReadableTime(sig_info->getSigningTime()));
     printf("  - Signature Validation: %s\n", getReadableSigState(sig_info->getSignatureValStatus()));