diff --git a/function_call.go b/function_call.go
index 74d3c3c..11cccb3 100644
--- a/function_call.go
+++ b/function_call.go
@@ -6,10 +6,10 @@ import (
 	"github.com/jackc/pgio"
 )
 
-type FunctionCall struct{
-	Function uint32
-	ArgFormatCodes []uint16
-	Arguments [][]byte
+type FunctionCall struct {
+	Function         uint32
+	ArgFormatCodes   []uint16
+	Arguments        [][]byte
 	ResultFormatCode uint16
 }
 
@@ -24,9 +24,9 @@ func (dst *FunctionCall) Decode(src []byte) error {
 	// Specifies the object ID of the function to call.
 	dst.Function = binary.BigEndian.Uint32(src[rp:])
 	rp += 4
-	// The number of argument format codes that follow (denoted C below). 
-	// This can be zero to indicate that there are no arguments or that the arguments all use the default format (text); 
-	// or one, in which case the specified format code is applied to all arguments; 
+	// The number of argument format codes that follow (denoted C below).
+	// This can be zero to indicate that there are no arguments or that the arguments all use the default format (text);
+	// or one, in which case the specified format code is applied to all arguments;
 	// or it can equal the actual number of arguments.
 	nArgumentCodes := int(binary.BigEndian.Uint16(src[rp:]))
 	rp += 2
@@ -37,36 +37,36 @@ func (dst *FunctionCall) Decode(src []byte) error {
 		if ac != 0 && ac != 1 {
 			return &invalidMessageFormatErr{messageType: "FunctionCall"}
 		}
-        argumentCodes[i] = ac
-        rp += 2
-    }
+		argumentCodes[i] = ac
+		rp += 2
+	}
 	dst.ArgFormatCodes = argumentCodes
-	
+
 	// Specifies the number of arguments being supplied to the function.
 	nArguments := int(binary.BigEndian.Uint16(src[rp:]))
 	rp += 2
 	arguments := make([][]byte, nArguments)
 	for i := 0; i < nArguments; i++ {
-		// The length of the argument value, in bytes (this count does not include itself). Can be zero. 
+		// The length of the argument value, in bytes (this count does not include itself). Can be zero.
 		// As a special case, -1 indicates a NULL argument value. No value bytes follow in the NULL case.
-        argumentLength := int(binary.BigEndian.Uint32(src[rp:]))
-        rp += 4
-        if argumentLength == -1 {
+		argumentLength := int(binary.BigEndian.Uint32(src[rp:]))
+		rp += 4
+		if argumentLength == -1 {
 			arguments[i] = nil
 		} else {
 			// The value of the argument, in the format indicated by the associated format code. n is the above length.
-			argumentValue := src[rp:rp+argumentLength]
+			argumentValue := src[rp : rp+argumentLength]
 			rp += argumentLength
 			arguments[i] = argumentValue
-        }
-    }
+		}
+	}
 	dst.Arguments = arguments
 	// The format code for the function result. Must presently be zero (text) or one (binary).
 	resultFormatCode := binary.BigEndian.Uint16(src[rp:])
 	if resultFormatCode != 0 && resultFormatCode != 1 {
-        return &invalidMessageFormatErr{messageType: "FunctionCall"}
-    }
-	dst.ResultFormatCode  = resultFormatCode
+		return &invalidMessageFormatErr{messageType: "FunctionCall"}
+	}
+	dst.ResultFormatCode = resultFormatCode
 	return nil
 }
 
@@ -78,17 +78,17 @@ func (src *FunctionCall) Encode(dst []byte) []byte {
 	dst = pgio.AppendUint32(dst, src.Function)
 	dst = pgio.AppendUint16(dst, uint16(len(src.ArgFormatCodes)))
 	for _, argFormatCode := range src.ArgFormatCodes {
-        dst = pgio.AppendUint16(dst, argFormatCode)
-    }
+		dst = pgio.AppendUint16(dst, argFormatCode)
+	}
 	dst = pgio.AppendUint16(dst, uint16(len(src.Arguments)))
 	for _, argument := range src.Arguments {
-        if argument == nil {
-            dst = pgio.AppendInt32(dst, -1)
-        } else {
-            dst = pgio.AppendInt32(dst, int32(len(argument)))
-            dst = append(dst, argument...)
-        }
-    }
+		if argument == nil {
+			dst = pgio.AppendInt32(dst, -1)
+		} else {
+			dst = pgio.AppendInt32(dst, int32(len(argument)))
+			dst = append(dst, argument...)
+		}
+	}
 	dst = pgio.AppendUint16(dst, src.ResultFormatCode)
 	pgio.SetInt32(dst[sp:], int32(len(dst[sp:])))
 	return dst
diff --git a/function_call_test.go b/function_call_test.go
index f158656..8c08bb2 100644
--- a/function_call_test.go
+++ b/function_call_test.go
@@ -1,7 +1,8 @@
 package pgproto3
 
 import (
-	"github.com/go-test/deep"
+	"encoding/binary"
+	"reflect"
 	"testing"
 )
 
@@ -17,7 +18,7 @@ func TestFunctionCall_EncodeDecode(t *testing.T) {
 		fields  fields
 		wantErr bool
 	}{
-		{"foo", fields{uint32(123), []uint16{0, 1, 0, 1}, [][]byte{[]byte("foo"), []byte("bar"), []byte("baz")}, uint16(0)}, false},
+		{"valid", fields{uint32(123), []uint16{0, 1, 0, 1}, [][]byte{[]byte("foo"), []byte("bar"), []byte("baz")}, uint16(1)}, false},
 		{"invalid format code", fields{uint32(123), []uint16{2, 1, 0, 1}, [][]byte{[]byte("foo"), []byte("bar"), []byte("baz")}, uint16(0)}, true},
 		{"invalid result format code", fields{uint32(123), []uint16{1, 1, 0, 1}, [][]byte{[]byte("foo"), []byte("bar"), []byte("baz")}, uint16(2)}, true},
 	}
@@ -30,15 +31,32 @@ func TestFunctionCall_EncodeDecode(t *testing.T) {
 				ResultFormatCode: tt.fields.ResultFormatCode,
 			}
 			encoded := src.Encode([]byte{})
-			decoded := &FunctionCall{}
-			err := decoded.Decode(encoded[5:])
-			if (err != nil) != tt.wantErr {
-                t.Errorf("FunctionCall.Decode() error = %v, wantErr %v", err, tt.wantErr)
-                return
-            }
-			if diff := deep.Equal(src, decoded); diff != nil {
-				t.Error(diff)
+			dst := &FunctionCall{}
+			// Check the header
+			msgTypeCode := encoded[0]
+			if msgTypeCode != 'F' {
+				t.Errorf("msgTypeCode %v should be 'F'", msgTypeCode)
+				return
+			}
+			// Check length, does not include type code character
+			l := binary.BigEndian.Uint32(encoded[1:5])
+			if int(l) != (len(encoded) - 1) {
+				t.Errorf("Incorrect message length, got = %v, wanted = %v", l, len(encoded))
+			}
+			// Check decoding works as expected
+			err := dst.Decode(encoded[5:])
+			if err != nil {
+				if !tt.wantErr {
+					t.Errorf("FunctionCall.Decode() error = %v, wantErr %v", err, tt.wantErr)
+				}
+				return
+			}
+
+			if !reflect.DeepEqual(src, dst) {
+				t.Error("difference after encode / decode cycle")
+				t.Errorf("src = %v", src)
+				t.Errorf("dst = %v", dst)
 			}
 		})
 	}
-}
\ No newline at end of file
+}
diff --git a/go.mod b/go.mod
index 030953b..36041a9 100644
--- a/go.mod
+++ b/go.mod
@@ -3,7 +3,6 @@ module github.com/jackc/pgproto3/v2
 go 1.12
 
 require (
-	github.com/go-test/deep v1.0.8
 	github.com/jackc/chunkreader/v2 v2.0.0
 	github.com/jackc/pgio v1.0.0
 	github.com/stretchr/testify v1.4.0
diff --git a/go.sum b/go.sum
index 765190c..dd9cd04 100644
--- a/go.sum
+++ b/go.sum
@@ -1,7 +1,5 @@
 github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
-github.com/go-test/deep v1.0.8 h1:TDsG77qcSprGbC6vTN8OuXp5g+J+b5Pcguhf7Zt61VM=
-github.com/go-test/deep v1.0.8/go.mod h1:5C2ZWiW0ErCdrYzpqxLbTX7MG14M9iiw8DgHncVwcsE=
 github.com/jackc/chunkreader/v2 v2.0.0 h1:DUwgMQuuPnS0rhMXenUtZpqZqrR/30NWY+qQvTpSvEs=
 github.com/jackc/chunkreader/v2 v2.0.0/go.mod h1:odVSm741yZoC3dpHEUXIqA9tQRhFrgOHwnPIn9lDKlk=
 github.com/jackc/pgio v1.0.0 h1:g12B9UwVnzGhueNavwioyEEpAmqMe1E/BN9ES+8ovkE=
@@ -11,7 +9,6 @@ github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZN
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/testify v1.4.0 h1:2E4SXV/wtOkTonXsotYi4li6zVWxYlZuYNCXe9XRJyk=
 github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
-gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v2 v2.2.2 h1:ZCJp+EgiOT7lHqUV2J862kp8Qj64Jo6az82+3Td9dZw=
 gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=