diff --git a/PVE/CLI/pveceph.pm b/PVE/CLI/pveceph.pm
index 356af282..6d77f6ad 100755
--- a/PVE/CLI/pveceph.pm
+++ b/PVE/CLI/pveceph.pm
@@ -177,7 +177,16 @@ __PACKAGE__->register_method ({
 	);
 
 	print "start installation\n";
+
+	# the install flag helps to determine when apt is done installing
+	my $install_flag_file = '/run/ceph-install-flag';
+	open(my $install_flag, '>', "${install_flag_file}") or
+	     die "could not open Ceph installation flag - $!\n";
+	close $install_flag;
+
 	if (system(@apt_install, @ceph_packages) != 0) {
+	    unlink $install_flag_file or
+		warn "Could not remove Ceph installation flag - $!";
 	    die "apt failed during ceph installation ($?)\n";
 	}
 
@@ -188,6 +197,9 @@ __PACKAGE__->register_method ({
 	    'systemctl', 'try-reload-or-restart', 'pvedaemon.service', 'pveproxy.service'
 	]);
 
+	unlink $install_flag_file or
+	    warn "Could not remove Ceph installation flag - $!";
+
 	return undef;
     }});
 
diff --git a/PVE/Ceph/Tools.pm b/PVE/Ceph/Tools.pm
index f54d837a..3f0818fd 100644
--- a/PVE/Ceph/Tools.pm
+++ b/PVE/Ceph/Tools.pm
@@ -155,7 +155,9 @@ sub check_ceph_installed {
 
     $service = 'ceph_bin' if !defined($service);
 
-    if (! -x $ceph_service->{$service}) {
+    # the flag file is checked as on a new installation, the binary gets
+    # extracted by dpkg before the installation is finished
+    if (! -x $ceph_service->{$service} || -f '/run/ceph-install-flag') {
 	die "binary not installed: $ceph_service->{$service}\n" if !$noerr;
 	return undef;
     }