diff --git a/.local/bin/getbib b/.local/bin/getbib
index 1d56dc8..bedc256 100755
--- a/.local/bin/getbib
+++ b/.local/bin/getbib
@@ -4,7 +4,7 @@
 if [ -f "$1" ]; then
 	# Try to get DOI from pdfinfo or pdftotext output.
 	doi=$(pdfinfo "$1" | grep -io "doi:.*") ||
-	doi=$(pdftotext "$1" 2>/dev/null - | grep -io "doi:\s*\S*" -m 1) ||
+	doi=$(pdftotext "$1" 2>/dev/null - | grep -io "doi:\s*\S\+[[:alnum:]]" -m 1) ||
 	exit 1
 else
 	doi="$1"