diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1185006..8610230 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,10 @@ Operators, you should copy/paste content of this content straight to your projec
 
 If you were at `firehose-core` version `1.0.0` and are bumping to `1.1.0`, you should copy the content between those 2 version to your own repository, replacing placeholder value `fire{chain}` with your chain's own binary.
 
+## v1.4.2 (Unreleased)
+
+* Fix parsing of flag 'common-index-block-sizes' from yaml config file
+
 ## v1.4.1
 
 ### Substreams bumped to v1.6.1
diff --git a/storage.go b/storage.go
index 0d6808b..4af5f3a 100644
--- a/storage.go
+++ b/storage.go
@@ -3,6 +3,8 @@ package firecore
 import (
 	"context"
 	"fmt"
+	"strconv"
+	"strings"
 
 	"github.com/spf13/viper"
 	"github.com/streamingfast/dstore"
@@ -54,7 +56,17 @@ func GetIndexStore(dataDir string) (indexStore dstore.Store, possibleIndexSizes
 		indexStore = s
 	}
 
-	for _, size := range viper.GetIntSlice("common-index-block-sizes") {
+	sizes := viper.GetIntSlice("common-index-block-sizes")
+	if len(sizes) == 0 {
+		// viper doesn't parse ints from yaml file correctly
+		for _, k := range strings.Split(viper.GetString("common-index-block-sizes"), ",") {
+			if asInt, _err := strconv.ParseInt(k, 10, 64); _err == nil {
+				sizes = append(sizes, int(asInt))
+			}
+		}
+
+	}
+	for _, size := range sizes {
 		if size < 0 {
 			return nil, nil, fmt.Errorf("invalid negative size for common-index-block-sizes: %d", size)
 		}