diff --git a/bind/genclasses.go b/bind/genclasses.go
index 8746ab2..a69d02b 100644
--- a/bind/genclasses.go
+++ b/bind/genclasses.go
@@ -381,7 +381,7 @@ func (g *ClassGen) genCMethodBody(cls *java.Class, f *java.Func, virtual bool) {
 		g.Printf("Nonvirtual")
 	}
 	if f.Ret != nil {
-		g.Printf(f.Ret.JNICallType())
+		g.Printf("%s", f.Ret.JNICallType())
 	} else {
 		g.Printf("Void")
 	}
@@ -430,7 +430,7 @@ func (g *ClassGen) genFuncDecl(local bool, fs *java.FuncSet) {
 		if i == len(fs.Params)-1 && fs.Variadic {
 			g.Printf("...")
 		}
-		g.Printf(g.goType(a, local))
+		g.Printf("%s", g.goType(a, local))
 	}
 	g.Printf(")")
 	if fs.Throws {
@@ -879,7 +879,7 @@ func (g *ClassGen) genInterface(cls *java.Class) {
 		if !g.isFuncSetSupported(fs) {
 			continue
 		}
-		g.Printf(fs.GoName)
+		g.Printf("%s", fs.GoName)
 		g.genFuncDecl(true, fs)
 		g.Printf("\n")
 	}
@@ -904,7 +904,7 @@ func flattenName(n string) string {
 	return strings.Replace(strings.Replace(n, ".", "_", -1), "$", "_", -1)
 }
 
-var (
+const (
 	classesPkgHeader = gobindPreamble + `
 package Java
 
diff --git a/bind/gengo.go b/bind/gengo.go
index 8087c7a..bb3634e 100644
--- a/bind/gengo.go
+++ b/bind/gengo.go
@@ -341,7 +341,7 @@ func (g *goGen) genInterface(obj *types.TypeName) {
 		g.Printf(") ")
 
 		if res.Len() == 1 {
-			g.Printf(g.typeString(res.At(0).Type()))
+			g.Printf("%s", g.typeString(res.At(0).Type()))
 		} else if res.Len() == 2 {
 			g.Printf("(%s, error)", g.typeString(res.At(0).Type()))
 		}
diff --git a/bind/genjava.go b/bind/genjava.go
index b197640..f1852a2 100644
--- a/bind/genjava.go
+++ b/bind/genjava.go
@@ -437,7 +437,7 @@ func (g *JavaGen) genConstructor(f *types.Func, n string, jcls bool) {
 			if i > 0 {
 				g.Printf(", ")
 			}
-			g.Printf(g.paramName(params, i))
+			g.Printf("%s", g.paramName(params, i))
 		}
 		g.Printf(");\n")
 	}
@@ -447,7 +447,7 @@ func (g *JavaGen) genConstructor(f *types.Func, n string, jcls bool) {
 		if i > 0 {
 			g.Printf(", ")
 		}
-		g.Printf(g.paramName(params, i))
+		g.Printf("%s", g.paramName(params, i))
 	}
 	g.Printf(");\n")
 	g.Printf("Seq.trackGoRef(refnum, this);\n")
@@ -757,21 +757,21 @@ func (g *JavaGen) genJNIFuncSignature(o *types.Func, sName string, jm *java.Func
 	g.Printf("Java_%s_", g.jniPkgName())
 	if sName != "" {
 		if proxy {
-			g.Printf(java.JNIMangle(g.className()))
+			g.Printf("%s", java.JNIMangle(g.className()))
 			// 0024 is the mangled form of $, for naming inner classes.
 			g.Printf("_00024proxy%s", sName)
 		} else {
-			g.Printf(java.JNIMangle(g.javaTypeName(sName)))
+			g.Printf("%s", java.JNIMangle(g.javaTypeName(sName)))
 		}
 	} else {
-		g.Printf(java.JNIMangle(g.className()))
+		g.Printf("%s", java.JNIMangle(g.className()))
 	}
 	g.Printf("_")
 	if jm != nil {
-		g.Printf(jm.JNIName)
+		g.Printf("%s", jm.JNIName)
 	} else {
 		oName := javaNameReplacer(lowerFirst(o.Name()))
-		g.Printf(java.JNIMangle(oName))
+		g.Printf("%s", java.JNIMangle(oName))
 	}
 	g.Printf("(JNIEnv* env, ")
 	if sName != "" {
@@ -839,9 +839,9 @@ func (g *JavaGen) genFuncSignature(o *types.Func, jm *java.Func, hasThis bool) {
 
 	g.Printf("%s ", ret)
 	if jm != nil {
-		g.Printf(jm.Name)
+		g.Printf("%s", jm.Name)
 	} else {
-		g.Printf(javaNameReplacer(lowerFirst(o.Name())))
+		g.Printf("%s", javaNameReplacer(lowerFirst(o.Name())))
 	}
 	g.Printf("(")
 	g.genFuncArgs(o, jm, hasThis)
diff --git a/bind/genobjc.go b/bind/genobjc.go
index d591413..b556212 100644
--- a/bind/genobjc.go
+++ b/bind/genobjc.go
@@ -1060,7 +1060,7 @@ func (g *ObjcGen) genStructH(obj *types.TypeName, t *types.Struct) {
 	if oinf != nil {
 		for _, sup := range oinf.supers {
 			if !sup.Protocol {
-				g.Printf(sup.Name)
+				g.Printf("%s", sup.Name)
 			} else {
 				prots = append(prots, sup.Name)
 			}
diff --git a/bind/genobjcw.go b/bind/genobjcw.go
index 1f5ccf6..731f1ae 100644
--- a/bind/genobjcw.go
+++ b/bind/genobjcw.go
@@ -286,14 +286,13 @@ func (g *ObjcWrapper) genCFuncDecl(prefix, name string, f *objc.Func) {
 	case ret != nil && returnsErr:
 		g.Printf("ret_%s", strings.Replace(g.cType(ret), " ", "_", -1))
 	case ret != nil:
-		g.Printf(g.cType(ret))
+		g.Printf("%s", g.cType(ret))
 	case returnsErr:
 		g.Printf("int")
 	default:
 		g.Printf("void")
 	}
-	g.Printf(" ")
-	g.Printf(prefix)
+	g.Printf(" %s", prefix)
 	if f.Static {
 		g.Printf("_s")
 	}
@@ -397,8 +396,7 @@ func (g *ObjcWrapper) genFuncBody(n *objc.Named, f *objc.Func, prefix string) {
 	if ret != nil || errParam != nil {
 		g.Printf("res := ")
 	}
-	g.Printf("C.")
-	g.Printf(prefix)
+	g.Printf("C.%s", prefix)
 	if f.Static {
 		g.Printf("_s")
 	}
@@ -575,7 +573,7 @@ func (g *ObjcWrapper) genInterface(n *objc.Named) {
 		if !g.isFuncSupported(f) {
 			continue
 		}
-		g.Printf(f.GoName)
+		g.Printf("%s", f.GoName)
 		g.genFuncDecl(true, f)
 		g.Printf("\n")
 	}
diff --git a/internal/binres/binres_test.go b/internal/binres/binres_test.go
index dbac875..7e4f214 100644
--- a/internal/binres/binres_test.go
+++ b/internal/binres/binres_test.go
@@ -8,6 +8,7 @@ import (
 	"bytes"
 	"encoding"
 	"encoding/xml"
+	"errors"
 	"fmt"
 	"io/ioutil"
 	"log"
@@ -103,7 +104,7 @@ func compareBytes(a, b []byte) error {
 			fmt.Fprint(buf, "... output truncated.\n")
 		}
 	}
-	return fmt.Errorf(buf.String())
+	return errors.New(buf.String())
 }
 
 func TestBootstrap(t *testing.T) {
@@ -329,7 +330,7 @@ func compareElements(have, want *XML) error {
 		}
 	}
 	if buf.Len() > 0 {
-		return fmt.Errorf(buf.String())
+		return errors.New(buf.String())
 	}
 	return nil
 }