diff --git a/mythril/mythril.py b/mythril/mythril.py
index b63cc137..a72a82d7 100644
--- a/mythril/mythril.py
+++ b/mythril/mythril.py
@@ -335,9 +335,9 @@ class Mythril(object):
                     verbose_report=False, max_depth=12):
 
         all_issues = []
+        if self.dynld and self.eth is None:
+            self.set_api_rpc_infura()
         for contract in (contracts or self.contracts):
-            if self.eth is None:
-                self.set_api_rpc_infura()
             sym = SymExecWrapper(contract, address,
                                  dynloader=DynLoader(self.eth) if self.dynld else None,
                                  max_depth=max_depth)
diff --git a/requirements.txt b/requirements.txt
index 13e88c78..aad67f69 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -2,7 +2,7 @@ configparser>=3.5.0
 coverage
 eth_abi>=1.0.0
 eth-account>=0.1.0a2
-ethereum>=2.3.0
+ethereum==2.3.1
 eth-hash>=0.1.0
 eth-keyfile>=0.5.1
 eth-keys>=0.2.0b3
diff --git a/setup.py b/setup.py
index 3cbf5f97..0e7c624d 100755
--- a/setup.py
+++ b/setup.py
@@ -305,7 +305,7 @@ setup(
     packages=find_packages(exclude=['contrib', 'docs', 'tests']),
 
     install_requires=[
-        'ethereum>=2.3.0',
+        'ethereum==2.3.1',
         'z3-solver>=4.5',
         'requests',
         'py-solc',