Index: os-prober/os-probes/mounted/x86/83haiku
===================================================================
--- os-prober.orig/os-probes/mounted/x86/83haiku
+++ os-prober/os-probes/mounted/x86/83haiku
@@ -13,7 +13,7 @@ case "$type" in
 	*) debug "$partition is not a BeFS partition: exiting"; exit 1 ;;
 esac
 
-if head -c 512 "$partition" | grep -qs "system.haiku_loader"; then
+if head -c 512 "$partition" | grep -aqs "system.haiku_loader"; then
 	debug "Stage 1 bootloader found"
 else
 	debug "Stage 1 bootloader not found: exiting"