diff --git a/fsmonitor.c b/fsmonitor.c
index 231e83a94d..1f4aa1b150 100644
--- a/fsmonitor.c
+++ b/fsmonitor.c
@@ -14,8 +14,13 @@ struct trace_key trace_fsmonitor = TRACE_KEY_INIT(FSMONITOR);
 static void fsmonitor_ewah_callback(size_t pos, void *is)
 {
 	struct index_state *istate = (struct index_state *)is;
-	struct cache_entry *ce = istate->cache[pos];
+	struct cache_entry *ce;
 
+	if (pos >= istate->cache_nr)
+		BUG("fsmonitor_dirty has more entries than the index (%"PRIuMAX" >= %u)",
+		    (uintmax_t)pos, istate->cache_nr);
+
+	ce = istate->cache[pos];
 	ce->ce_flags &= ~CE_FSMONITOR_VALID;
 }
 
@@ -50,17 +55,24 @@ int read_fsmonitor_extension(struct index_state *istate, const void *data,
 	}
 	istate->fsmonitor_dirty = fsmonitor_dirty;
 
+	if (istate->fsmonitor_dirty->bit_size > istate->cache_nr)
+		BUG("fsmonitor_dirty has more entries than the index (%"PRIuMAX" > %u)",
+		    (uintmax_t)istate->fsmonitor_dirty->bit_size, istate->cache_nr);
+
 	trace_printf_key(&trace_fsmonitor, "read fsmonitor extension successful");
 	return 0;
 }
 
 void fill_fsmonitor_bitmap(struct index_state *istate)
 {
-	unsigned int i;
+	unsigned int i, skipped = 0;
 	istate->fsmonitor_dirty = ewah_new();
-	for (i = 0; i < istate->cache_nr; i++)
-		if (!(istate->cache[i]->ce_flags & CE_FSMONITOR_VALID))
-			ewah_set(istate->fsmonitor_dirty, i);
+	for (i = 0; i < istate->cache_nr; i++) {
+		if (istate->cache[i]->ce_flags & CE_REMOVE)
+			skipped++;
+		else if (!(istate->cache[i]->ce_flags & CE_FSMONITOR_VALID))
+			ewah_set(istate->fsmonitor_dirty, i - skipped);
+	}
 }
 
 void write_fsmonitor_extension(struct strbuf *sb, struct index_state *istate)
@@ -71,6 +83,10 @@ void write_fsmonitor_extension(struct strbuf *sb, struct index_state *istate)
 	uint32_t ewah_size = 0;
 	int fixup = 0;
 
+	if (istate->fsmonitor_dirty->bit_size > istate->cache_nr)
+		BUG("fsmonitor_dirty has more entries than the index (%"PRIuMAX" > %u)",
+		    (uintmax_t)istate->fsmonitor_dirty->bit_size, istate->cache_nr);
+
 	put_be32(&hdr_version, INDEX_EXTENSION_VERSION);
 	strbuf_add(sb, &hdr_version, sizeof(uint32_t));
 
@@ -236,6 +252,9 @@ void tweak_fsmonitor(struct index_state *istate)
 			}
 
 			/* Mark all previously saved entries as dirty */
+			if (istate->fsmonitor_dirty->bit_size > istate->cache_nr)
+				BUG("fsmonitor_dirty has more entries than the index (%"PRIuMAX" > %u)",
+				    (uintmax_t)istate->fsmonitor_dirty->bit_size, istate->cache_nr);
 			ewah_each_bit(istate->fsmonitor_dirty, fsmonitor_ewah_callback, istate);
 
 			/* Now mark the untracked cache for fsmonitor usage */
diff --git a/t/t7519-status-fsmonitor.sh b/t/t7519-status-fsmonitor.sh
index 81a375fa0f..d8df990972 100755
--- a/t/t7519-status-fsmonitor.sh
+++ b/t/t7519-status-fsmonitor.sh
@@ -354,4 +354,21 @@ test_expect_success 'discard_index() also discards fsmonitor info' '
 	test_cmp expect actual
 '
 
+# Test staging/unstaging files that appear at the end of the index.  Test
+# file names begin with 'z' so that they are sorted to the end of the index.
+test_expect_success 'status succeeds after staging/unstaging ' '
+	test_create_repo fsmonitor-stage-unstage &&
+	(
+		cd fsmonitor-stage-unstage &&
+		test_commit initial &&
+		git update-index --fsmonitor &&
+		removed=$(test_seq 1 100 | sed "s/^/z/") &&
+		touch $removed &&
+		git add $removed &&
+		git config core.fsmonitor "$TEST_DIRECTORY/t7519/fsmonitor-env" &&
+		FSMONITOR_LIST="$removed" git restore -S $removed &&
+		FSMONITOR_LIST="$removed" git status
+	)
+'
+
 test_done
diff --git a/t/t7519/fsmonitor-env b/t/t7519/fsmonitor-env
new file mode 100755
index 0000000000..8f1f7ab164
--- /dev/null
+++ b/t/t7519/fsmonitor-env
@@ -0,0 +1,24 @@
+#!/bin/sh
+#
+# An test hook script to integrate with git to test fsmonitor.
+#
+# The hook is passed a version (currently 1) and a time in nanoseconds
+# formatted as a string and outputs to stdout all files that have been
+# modified since the given time. Paths must be relative to the root of
+# the working tree and separated by a single NUL.
+#
+#echo "$0 $*" >&2
+
+if test "$#" -ne 2
+then
+	echo "$0: exactly 2 arguments expected" >&2
+	exit 2
+fi
+
+if test "$1" != 1
+then
+	echo "Unsupported core.fsmonitor hook version." >&2
+	exit 1
+fi
+
+printf '%s\n' $FSMONITOR_LIST