diff --git a/guilt-graph b/guilt-graph
index b3469dc..56d0e77 100755
--- a/guilt-graph
+++ b/guilt-graph
@@ -17,8 +17,13 @@ fi
 
 patchname="$1"
 
-bottom=`git rev-parse refs/patches/$branch/$(head_n 1 < "$applied")`
-base=`git rev-parse $bottom^`
+bottompatch=$(head_n 1 < "$applied")
+if [ -z "$bottompatch" ]; then
+	echo "No patch applied." >&2
+	exit 1
+fi
+
+base=`git rev-parse "refs/patches/${branch}/${bottompatch}^"`
 
 if [ -z "$patchname" ]; then
 	top=`git rev-parse HEAD`
diff --git a/regression/t-033.out b/regression/t-033.out
new file mode 100644
index 0000000..76613f9
--- /dev/null
+++ b/regression/t-033.out
@@ -0,0 +1,3 @@
+% setup_repo
+% guilt graph
+No patch applied.
diff --git a/regression/t-033.sh b/regression/t-033.sh
new file mode 100755
index 0000000..a3a8981
--- /dev/null
+++ b/regression/t-033.sh
@@ -0,0 +1,13 @@
+#!/bin/bash
+#
+# Test the graph code
+#
+
+source "$REG_DIR/scaffold"
+
+cmd setup_repo
+
+# Check that "guilt graph" gives a proper "No patch applied" error
+# message when no patches are applied.  (An older version of guilt
+# used to enter an endless loop in this situation.)
+shouldfail guilt graph