diff --git a/state/state.go b/state/state.go
index 7e22e04d1..4e0fa75b5 100644
--- a/state/state.go
+++ b/state/state.go
@@ -324,12 +324,9 @@ func MakeGenesisStateFromFile(db dbm.DB, genDocFile string) *State {
 //
 // Used in tests.
 func MakeGenesisState(db dbm.DB, genDoc *types.GenesisDoc) *State {
-	if len(genDoc.Validators) == 0 {
-		cmn.Exit(cmn.Fmt("The genesis file has no validators"))
-	}
-
-	if genDoc.GenesisTime.IsZero() {
-		genDoc.GenesisTime = time.Now()
+	err := genDoc.ValidateAndComplete()
+	if err != nil {
+		cmn.Exit(cmn.Fmt("Error in genesis file: %v", err))
 	}
 
 	// Make validators slice
diff --git a/types/genesis.go b/types/genesis.go
index b7762c576..79bf63c8b 100644
--- a/types/genesis.go
+++ b/types/genesis.go
@@ -52,26 +52,48 @@ func (genDoc *GenesisDoc) ValidatorHash() []byte {
 	return vset.Hash()
 }
 
-//------------------------------------------------------------
-// Make genesis state from file
-
-// GenesisDocFromJSON unmarshalls JSON data into a GenesisDoc.
-func GenesisDocFromJSON(jsonBlob []byte) (*GenesisDoc, error) {
-	genDoc := GenesisDoc{}
-	err := json.Unmarshal(jsonBlob, &genDoc)
+// ValidateAndComplete checks that all necessary fields are present
+// and fills in defaults for optional fields left empty
+func (genDoc *GenesisDoc) ValidateAndComplete() error {
 
-	// validate genesis
 	if genDoc.ChainID == "" {
-		return nil, errors.Errorf("Genesis doc must include non-empty chain_id")
+		return errors.Errorf("Genesis doc must include non-empty chain_id")
 	}
+
 	if genDoc.ConsensusParams == nil {
 		genDoc.ConsensusParams = cfg.DefaultConsensusParams()
 	} else {
 		if err := genDoc.ConsensusParams.Validate(); err != nil {
-			return nil, err
+			return err
 		}
 	}
 
+	if len(genDoc.Validators) == 0 {
+		return errors.Errorf("The genesis file must have at least one validator")
+	}
+
+	if genDoc.GenesisTime.IsZero() {
+		genDoc.GenesisTime = time.Now()
+	}
+
+	return nil
+}
+
+//------------------------------------------------------------
+// Make genesis state from file
+
+// GenesisDocFromJSON unmarshalls JSON data into a GenesisDoc.
+func GenesisDocFromJSON(jsonBlob []byte) (*GenesisDoc, error) {
+	genDoc := GenesisDoc{}
+	err := json.Unmarshal(jsonBlob, &genDoc)
+	if err != nil {
+		return nil, err
+	}
+
+	if err := genDoc.ValidateAndComplete(); err != nil {
+		return nil, err
+	}
+
 	return &genDoc, err
 }