diff --git a/core/peer/config.go b/core/peer/config.go
index 3797f1911db..35551fe45c3 100644
--- a/core/peer/config.go
+++ b/core/peer/config.go
@@ -276,13 +276,12 @@ func (c *Config) load() error {
 	}
 
 	c.ChaincodePull = viper.GetBool("chaincode.pull")
-	var externalBuilders []ExternalBuilder
 
-	if err := yaml.UnmarshalStrict([]byte(viper.GetString("chaincode.externalBuilders")), &externalBuilders); err != nil {
-		return errors.Wrap(err, "unmarshalling 'chaincode.externalBuilders' into yaml")
+	c.ExternalBuilders, err = getExternalBuildersConfig()
+	if err != nil {
+		return errors.Wrap(err, "getting external builders config")
 	}
 
-	c.ExternalBuilders = externalBuilders
 	for builderIndex, builder := range c.ExternalBuilders {
 		if builder.Path == "" {
 			return fmt.Errorf("invalid external builder configuration, path attribute missing in one or more builders")
@@ -290,7 +289,7 @@ func (c *Config) load() error {
 		if builder.Name == "" {
 			return fmt.Errorf("external builder at path %s has no name attribute", builder.Path)
 		}
-		if builder.Environment != nil && builder.PropagateEnvironment == nil {
+		if builder.Environment != nil && len(builder.PropagateEnvironment) == 0 {
 			c.ExternalBuilders[builderIndex].PropagateEnvironment = builder.Environment
 		}
 	}
@@ -477,3 +476,24 @@ func GetClientCertificate() (tls.Certificate, error) {
 	}
 	return cert, nil
 }
+
+// this method is needed because old viper (< 1.1.0) has bugs in automatic env option
+func getExternalBuildersConfig() ([]ExternalBuilder, error) {
+	var externalBuilders []ExternalBuilder
+
+	if viper.IsSet("chaincode.externalBuilders") {
+		// when defined as an env var the value is string, then we need to parse it as a yaml string
+		if extBuildersString := viper.GetString("chaincode.externalBuilders"); extBuildersString != "" {
+			if err := yaml.UnmarshalStrict([]byte(extBuildersString), &externalBuilders); err != nil {
+				return nil, errors.Wrap(err, "unmarshalling 'chaincode.externalBuilders' into yaml")
+			}
+		} else {
+			// otherwise we expect it to be a map, core.yaml is unmarshalled into a generic struct map[string]interface and then mapstructure.Decode has to be used.
+			if err := viper.UnmarshalKey("chaincode.externalBuilders", &externalBuilders); err != nil {
+				return nil, err
+			}
+		}
+	}
+
+	return externalBuilders, nil
+}
diff --git a/core/peer/config_test.go b/core/peer/config_test.go
index 80f0981dc6b..caf786fc5be 100644
--- a/core/peer/config_test.go
+++ b/core/peer/config_test.go
@@ -7,6 +7,7 @@ package peer
 
 import (
 	"crypto/tls"
+	"gopkg.in/yaml.v2"
 	"io/ioutil"
 	"net"
 	"os"
@@ -308,7 +309,19 @@ func TestGlobalConfig(t *testing.T) {
 	viper.Set("metrics.statsd.prefix", "testPrefix")
 
 	viper.Set("chaincode.pull", false)
-	viper.Set("chaincode.externalBuilders", "[{name: relative, path: relative/plugin_dir}, {name: absolute, path: /absolute/plugin_dir}]")
+
+	extBuildersConfig, err := yaml.Marshal([]ExternalBuilder{
+		{
+			Path: "relative/plugin_dir",
+			Name: "relative",
+		},
+		{
+			Path: "/absolute/plugin_dir",
+			Name: "absolute",
+		},
+	})
+	require.NoError(t, err)
+	viper.Set("chaincode.externalBuilders", extBuildersConfig)
 
 	coreConfig, err := GlobalConfig()
 	assert.NoError(t, err)
@@ -343,12 +356,16 @@ func TestGlobalConfig(t *testing.T) {
 		ChaincodePull: false,
 		ExternalBuilders: []ExternalBuilder{
 			{
-				Path: "relative/plugin_dir",
-				Name: "relative",
+				Path:                 "relative/plugin_dir",
+				Name:                 "relative",
+				PropagateEnvironment: []string{},
+				Environment:          []string{},
 			},
 			{
-				Path: "/absolute/plugin_dir",
-				Name: "absolute",
+				Path:                 "/absolute/plugin_dir",
+				Name:                 "absolute",
+				PropagateEnvironment: []string{},
+				Environment:          []string{},
 			},
 		},
 		OperationsListenAddress:         "127.0.0.1:9443",
@@ -396,7 +413,26 @@ func TestGlobalConfigDefault(t *testing.T) {
 func TestPropagateEnvironment(t *testing.T) {
 	defer viper.Reset()
 	viper.Set("peer.address", "localhost:8080")
-	viper.Set("chaincode.externalBuilders", "[{name: testName, environmentWhitelist: [KEY=VALUE], path: /testPath}, {name: testName, propagateEnvironment: [KEY=VALUE], path: /testPath}, {name: testName, environmentWhitelist: [KEY=VALUE], propagateEnvironment: [KEY=VALUE2], path: /testPath}]")
+	viper.Set("chaincode.externalBuilders", []ExternalBuilder{
+		{
+			Name:                 "testName",
+			Environment:          []string{"KEY=VALUE"},
+			PropagateEnvironment: []string{},
+			Path:                 "/testPath",
+		},
+		{
+			Name:                 "testName",
+			PropagateEnvironment: []string{"KEY=VALUE"},
+			Environment:          []string{},
+			Path:                 "/testPath",
+		},
+		{
+			Name:                 "testName",
+			Environment:          []string{"KEY=VALUE"},
+			PropagateEnvironment: []string{"KEY=VALUE2"},
+			Path:                 "/testPath",
+		},
+	})
 	coreConfig, err := GlobalConfig()
 	assert.NoError(t, err)
 
@@ -416,6 +452,7 @@ func TestPropagateEnvironment(t *testing.T) {
 			{
 				Name:                 "testName",
 				PropagateEnvironment: []string{"KEY=VALUE"},
+				Environment:          []string{},
 				Path:                 "/testPath",
 			},
 			{
@@ -432,7 +469,22 @@ func TestPropagateEnvironment(t *testing.T) {
 func TestExternalBuilderConfigAsEnvVar(t *testing.T) {
 	defer viper.Reset()
 	viper.Set("peer.address", "localhost:8080")
-	viper.Set("chaincode.externalBuilders", "[{name: relative, path: relative/plugin_dir, propagateEnvironment: [ENVVAR_NAME_TO_PROPAGATE_FROM_PEER, GOPROXY]}, {name: absolute, path: /absolute/plugin_dir}]")
+	extBuildersConfig, err := yaml.Marshal([]ExternalBuilder{
+		{
+			Path:                 "relative/plugin_dir",
+			Name:                 "relative",
+			PropagateEnvironment: []string{"ENVVAR_NAME_TO_PROPAGATE_FROM_PEER", "GOPROXY"},
+		},
+		{
+			Path:                 "/absolute/plugin_dir",
+			Name:                 "absolute",
+			PropagateEnvironment: nil,
+		},
+	})
+	require.NoError(t, err)
+
+	viper.Set("chaincode.externalBuilders", extBuildersConfig)
+
 	coreConfig, err := GlobalConfig()
 	require.NoError(t, err)
 
@@ -441,10 +493,13 @@ func TestExternalBuilderConfigAsEnvVar(t *testing.T) {
 			Path:                 "relative/plugin_dir",
 			Name:                 "relative",
 			PropagateEnvironment: []string{"ENVVAR_NAME_TO_PROPAGATE_FROM_PEER", "GOPROXY"},
+			Environment:          []string{},
 		},
 		{
-			Path: "/absolute/plugin_dir",
-			Name: "absolute",
+			Path:                 "/absolute/plugin_dir",
+			Name:                 "absolute",
+			PropagateEnvironment: []string{},
+			Environment:          []string{},
 		},
 	}, coreConfig.ExternalBuilders)
 }
@@ -452,7 +507,12 @@ func TestExternalBuilderConfigAsEnvVar(t *testing.T) {
 func TestMissingExternalBuilderPath(t *testing.T) {
 	defer viper.Reset()
 	viper.Set("peer.address", "localhost:8080")
-	viper.Set("chaincode.externalBuilders", "[{name: testName}]")
+
+	viper.Set("chaincode.externalBuilders", []ExternalBuilder{
+		{
+			Name: "testName",
+		},
+	})
 	_, err := GlobalConfig()
 	assert.EqualError(t, err, "invalid external builder configuration, path attribute missing in one or more builders")
 }
@@ -460,7 +520,13 @@ func TestMissingExternalBuilderPath(t *testing.T) {
 func TestMissingExternalBuilderName(t *testing.T) {
 	defer viper.Reset()
 	viper.Set("peer.address", "localhost:8080")
-	viper.Set("chaincode.externalBuilders", "[{path: relative/plugin_dir}]")
+
+	viper.Set("chaincode.externalBuilders", []ExternalBuilder{
+		{
+			Path: "relative/plugin_dir",
+		},
+	})
+
 	_, err := GlobalConfig()
 	assert.EqualError(t, err, "external builder at path relative/plugin_dir has no name attribute")
 }