diff --git a/src/blame.c b/src/blame.c
index 2daf91591..2c8584ba5 100644
--- a/src/blame.c
+++ b/src/blame.c
@@ -178,7 +178,7 @@ const git_blame_hunk *git_blame_get_hunk_byline(git_blame *blame, size_t lineno)
 	return NULL;
 }
 
-static void normalize_options(
+static int normalize_options(
 		git_blame_options *out,
 		const git_blame_options *in,
 		git_repository *repo)
@@ -190,7 +190,9 @@ static void normalize_options(
 
 	/* No newest_commit => HEAD */
 	if (git_oid_iszero(&out->newest_commit)) {
-		git_reference_name_to_id(&out->newest_commit, repo, "HEAD");
+		if (git_reference_name_to_id(&out->newest_commit, repo, "HEAD") < 0) {
+			return -1;
+		}
 	}
 
 	/* min_line 0 really means 1 */
@@ -204,6 +206,8 @@ static void normalize_options(
 		out->flags |= GIT_BLAME_TRACK_COPIES_SAME_COMMIT_MOVES;
 	if (out->flags & GIT_BLAME_TRACK_COPIES_SAME_COMMIT_MOVES)
 		out->flags |= GIT_BLAME_TRACK_COPIES_SAME_FILE;
+
+	return 0;
 }
 
 static git_blame_hunk *split_hunk_in_vector(
@@ -362,7 +366,8 @@ int git_blame_file(
 	git_blame *blame = NULL;
 
 	assert(out && repo && path);
-	normalize_options(&normOptions, options, repo);
+	if ((error = normalize_options(&normOptions, options, repo)) < 0)
+		goto on_error;
 
 	blame = git_blame__alloc(repo, normOptions, path);
 	GITERR_CHECK_ALLOC(blame);
diff --git a/src/blame_git.c b/src/blame_git.c
index b8b568285..700207edb 100644
--- a/src/blame_git.c
+++ b/src/blame_git.c
@@ -525,7 +525,8 @@ static int pass_blame(git_blame *blame, git_blame__origin *origin, uint32_t opt)
 		if (sg_origin[i])
 			continue;
 
-		git_commit_parent(&p, origin->commit, i);
+		if ((error = git_commit_parent(&p, origin->commit, i)) < 0)
+			goto finish;
 		porigin = find_origin(blame, p, origin);
 
 		if (!porigin)
diff --git a/src/config_cache.c b/src/config_cache.c
index c859ec148..dbea871b9 100644
--- a/src/config_cache.c
+++ b/src/config_cache.c
@@ -86,7 +86,8 @@ int git_config__cvar(int *out, git_config *config, git_cvar_cached cvar)
 	struct map_data *data = &_cvar_maps[(int)cvar];
 	git_config_entry *entry;
 
-	git_config__lookup_entry(&entry, config, data->cvar_name, false);
+	if ((error = git_config__lookup_entry(&entry, config, data->cvar_name, false)) < 0)
+		return error;
 
 	if (!entry)
 		*out = data->default_value;
diff --git a/src/config_file.c b/src/config_file.c
index 65971b930..584b9fa82 100644
--- a/src/config_file.c
+++ b/src/config_file.c
@@ -232,7 +232,10 @@ static refcounted_strmap *refcounted_strmap_take(diskfile_header *h)
 {
 	refcounted_strmap *map;
 
-	git_mutex_lock(&h->values_mutex);
+	if (git_mutex_lock(&h->values_mutex) < 0) {
+	    giterr_set(GITERR_OS, "Failed to lock config backend");
+	    return NULL;
+	}
 
 	map = h->values;
 	git_atomic_inc(&map->refcount);
@@ -318,7 +321,10 @@ static int config__refresh(git_config_backend *cfg)
 	if ((error = config_read(values->values, b, reader, b->level, 0)) < 0)
 		goto out;
 
-	git_mutex_lock(&b->header.values_mutex);
+	if ((error = git_mutex_lock(&b->header.values_mutex)) < 0) {
+		giterr_set(GITERR_OS, "Failed to lock config backend");
+		goto out;
+	}
 
 	tmp = b->header.values;
 	b->header.values = values;
@@ -460,7 +466,8 @@ static int config_set(git_config_backend *cfg, const char *name, const char *val
 	if ((rval = git_config__normalize_name(name, &key)) < 0)
 		return rval;
 
-	map = refcounted_strmap_take(&b->header);
+	if ((map = refcounted_strmap_take(&b->header)) == NULL)
+		return -1;
 	values = map->values;
 
 	/*
@@ -527,7 +534,8 @@ static int config_get(git_config_backend *cfg, const char *key, git_config_entry
 	if (!h->parent.readonly && ((error = config_refresh(cfg)) < 0))
 		return error;
 
-	map = refcounted_strmap_take(h);
+	if ((map = refcounted_strmap_take(h)) == NULL)
+		return -1;
 	values = map->values;
 
 	pos = git_strmap_lookup_index(values, key);
@@ -565,7 +573,8 @@ static int config_set_multivar(
 	if ((result = git_config__normalize_name(name, &key)) < 0)
 		return result;
 
-	map = refcounted_strmap_take(&b->header);
+	if ((map = refcounted_strmap_take(&b->header)) == NULL)
+		return -1;
 	values = b->header.values->values;
 
 	pos = git_strmap_lookup_index(values, key);
@@ -610,7 +619,8 @@ static int config_delete(git_config_backend *cfg, const char *name)
 	if ((result = git_config__normalize_name(name, &key)) < 0)
 		return result;
 
-	map = refcounted_strmap_take(&b->header);
+	if ((map = refcounted_strmap_take(&b->header)) == NULL)
+		return -1;
 	values = b->header.values->values;
 
 	pos = git_strmap_lookup_index(values, key);
@@ -649,7 +659,8 @@ static int config_delete_multivar(git_config_backend *cfg, const char *name, con
 	if ((result = git_config__normalize_name(name, &key)) < 0)
 		return result;
 
-	map = refcounted_strmap_take(&b->header);
+	if ((map = refcounted_strmap_take(&b->header)) == NULL)
+		return -1;
 	values = b->header.values->values;
 
 	pos = git_strmap_lookup_index(values, key);
@@ -832,7 +843,8 @@ static int config_readonly_open(git_config_backend *cfg, git_config_level_t leve
 	/* We're just copying data, don't care about the level */
 	GIT_UNUSED(level);
 
-	src_map = refcounted_strmap_take(src_header);
+	if ((src_map = refcounted_strmap_take(src_header)) == NULL)
+		return -1;
 	b->header.values = src_map;
 
 	return 0;
diff --git a/src/filebuf.c b/src/filebuf.c
index 17efe872e..101d5082a 100644
--- a/src/filebuf.c
+++ b/src/filebuf.c
@@ -70,6 +70,7 @@ static int lock_file(git_filebuf *file, int flags, mode_t mode)
 		git_file source;
 		char buffer[FILEIO_BUFSIZE];
 		ssize_t read_bytes;
+		int error;
 
 		source = p_open(file->path_original, O_RDONLY);
 		if (source < 0) {
@@ -80,7 +81,8 @@ static int lock_file(git_filebuf *file, int flags, mode_t mode)
 		}
 
 		while ((read_bytes = p_read(source, buffer, sizeof(buffer))) > 0) {
-			p_write(file->fd, buffer, read_bytes);
+			if ((error = p_write(file->fd, buffer, read_bytes)) < 0)
+				break;
 			if (file->compute_digest)
 				git_hash_update(&file->digest, buffer, read_bytes);
 		}
@@ -90,6 +92,9 @@ static int lock_file(git_filebuf *file, int flags, mode_t mode)
 		if (read_bytes < 0) {
 			giterr_set(GITERR_OS, "Failed to read file '%s'", file->path_original);
 			return -1;
+		} else if (error < 0) {
+			giterr_set(GITERR_OS, "Failed to write file '%s'", file->path_lock);
+			return -1;
 		}
 	}
 
diff --git a/src/refdb_fs.c b/src/refdb_fs.c
index f6ed7201a..f978038e6 100644
--- a/src/refdb_fs.c
+++ b/src/refdb_fs.c
@@ -962,6 +962,7 @@ static int packed_write(refdb_fs_backend *backend)
 
 	for (i = 0; i < git_sortedcache_entrycount(refcache); ++i) {
 		struct packref *ref = git_sortedcache_entry(refcache, i);
+		assert(ref);
 
 		if (packed_find_peel(backend, ref) < 0)
 			goto fail;