diff --git a/src/read.c b/src/read.c
index adbd5e9..7e53e72 100644
--- a/src/read.c
+++ b/src/read.c
@@ -788,7 +788,7 @@
 static avifResult avifCheckItemID(const char * boxFourcc, uint32_t itemID, avifDiagnostics * diag)
 {
     if (itemID == 0) {
-        avifDiagnosticsPrintf(diag, "Box[%4s] has an invalid item ID [%u]", boxFourcc, itemID);
+        avifDiagnosticsPrintf(diag, "Box[%.4s] has an invalid item ID [%u]", boxFourcc, itemID);
         return AVIF_RESULT_BMFF_PARSE_FAILED;
     }
     return AVIF_RESULT_OK;
@@ -2261,12 +2261,12 @@
     uint32_t marker, version;
     AVIF_CHECK(avifROStreamReadBits(s, &marker, /*bitCount=*/1)); // unsigned int (1) marker = 1;
     if (!marker) {
-        avifDiagnosticsPrintf(diag, "%s contains illegal marker: [%u]", configPropName, marker);
+        avifDiagnosticsPrintf(diag, "%.4s contains illegal marker: [%u]", configPropName, marker);
         return AVIF_FALSE;
     }
     AVIF_CHECK(avifROStreamReadBits(s, &version, /*bitCount=*/7)); // unsigned int (7) version = 1;
     if (version != 1) {
-        avifDiagnosticsPrintf(diag, "%s contains illegal version: [%u]", configPropName, version);
+        avifDiagnosticsPrintf(diag, "%.4s contains illegal version: [%u]", configPropName, version);
         return AVIF_FALSE;
     }