diff --git a/packages/sooho-flattener/package.json b/packages/sooho-flattener/package.json
index b889e659..9e7d4a8c 100644
--- a/packages/sooho-flattener/package.json
+++ b/packages/sooho-flattener/package.json
@@ -16,7 +16,7 @@
   "license": "GPL-3.0",
   "dependencies": {
     "find-node-modules": "^2.0.0",
-    "semver": "^6.0.0",
+    "semver": "^6.3.1",
     "solidity-parser-antlr": "^0.4.2"
   },
   "private": true,
diff --git a/packages/sooho-flattener/yarn.lock b/packages/sooho-flattener/yarn.lock
index dfcc44f9..d5c99f99 100644
--- a/packages/sooho-flattener/yarn.lock
+++ b/packages/sooho-flattener/yarn.lock
@@ -1204,10 +1204,10 @@ semver@^5.5.0, semver@^5.5.1:
   resolved "https://registry.yarnpkg.com/semver/-/semver-5.7.0.tgz#790a7cf6fea5459bac96110b29b60412dc8ff96b"
   integrity sha512-Ya52jSX2u7QKghxeoFGpLwCtGlt7j0oY9DYb5apt9nPlJ42ID+ulTXESnt/qAQcoSERyZ5sl3LDIOw0nAn/5DA==
 
-semver@^6.0.0:
-  version "6.0.0"
-  resolved "https://registry.yarnpkg.com/semver/-/semver-6.0.0.tgz#05e359ee571e5ad7ed641a6eec1e547ba52dea65"
-  integrity sha512-0UewU+9rFapKFnlbirLi3byoOuhrSsli/z/ihNnvM24vgF+8sNBiI1LZPBSH9wJKUwaUbw+s3hToDLCXkrghrQ==
+semver@^6.3.1:
+  version "6.3.1"
+  resolved "https://registry.yarnpkg.com/semver/-/semver-6.3.1.tgz#556d2ef8689146e46dcea4bfdd095f3434dffcb4"
+  integrity sha512-BR7VvDCVHO+q2xBEWskxS6DJE1qRnb7DxzUrogb71CWoSficBxYsiAGd+Kl0mmq/MprG9yArRkyrQxTO6XjMzA==
 
 set-value@^0.4.3:
   version "0.4.3"