diff --git a/src/cmd/compile/internal/gc/const.go b/src/cmd/compile/internal/gc/const.go
index bd307116e8..24c0fba523 100644
--- a/src/cmd/compile/internal/gc/const.go
+++ b/src/cmd/compile/internal/gc/const.go
@@ -6,6 +6,7 @@ package gc
 
 import (
 	"cmd/internal/src"
+	"math/big"
 	"strings"
 )
 
@@ -455,19 +456,33 @@ func toint(v Val) Val {
 
 	case *Mpflt:
 		i := new(Mpint)
-		if i.SetFloat(u) < 0 {
-			msg := "constant %v truncated to integer"
-			// provide better error message if SetFloat failed because f was too large
-			if u.Val.IsInt() {
-				msg = "constant %v overflows integer"
+		if !i.SetFloat(u) {
+			if i.Ovf {
+				yyerror("integer too large")
+			} else {
+				// The value of u cannot be represented as an integer;
+				// so we need to print an error message.
+				// Unfortunately some float values cannot be
+				// reasonably formatted for inclusion in an error
+				// message (example: 1 + 1e-100), so first we try to
+				// format the float; if the truncation resulted in
+				// something that looks like an integer we omit the
+				// value from the error message.
+				// (See issue #11371).
+				var t big.Float
+				t.Parse(fconv(u, FmtSharp), 10)
+				if t.IsInt() {
+					yyerror("constant truncated to integer")
+				} else {
+					yyerror("constant %v truncated to integer", fconv(u, FmtSharp))
+				}
 			}
-			yyerror(msg, fconv(u, FmtSharp))
 		}
 		v.U = i
 
 	case *Mpcplx:
 		i := new(Mpint)
-		if i.SetFloat(&u.Real) < 0 || u.Imag.CmpFloat64(0) != 0 {
+		if !i.SetFloat(&u.Real) || u.Imag.CmpFloat64(0) != 0 {
 			yyerror("constant %v%vi truncated to integer", fconv(&u.Real, FmtSharp), fconv(&u.Imag, FmtSharp|FmtSign))
 		}
 
diff --git a/src/cmd/compile/internal/gc/mpint.go b/src/cmd/compile/internal/gc/mpint.go
index fba82607b5..f4efde3751 100644
--- a/src/cmd/compile/internal/gc/mpint.go
+++ b/src/cmd/compile/internal/gc/mpint.go
@@ -36,15 +36,16 @@ func (a *Mpint) Set(b *Mpint) {
 	a.Val.Set(&b.Val)
 }
 
-func (a *Mpint) SetFloat(b *Mpflt) int {
+func (a *Mpint) SetFloat(b *Mpflt) bool {
 	// avoid converting huge floating-point numbers to integers
 	// (2*Mpprec is large enough to permit all tests to pass)
 	if b.Val.MantExp(nil) > 2*Mpprec {
-		return -1
+		a.SetOverflow()
+		return false
 	}
 
 	if _, acc := b.Val.Int(&a.Val); acc == big.Exact {
-		return 0
+		return true
 	}
 
 	const delta = 16 // a reasonably small number of bits > 0
@@ -55,17 +56,18 @@ func (a *Mpint) SetFloat(b *Mpflt) int {
 	t.SetMode(big.ToZero)
 	t.Set(&b.Val)
 	if _, acc := t.Int(&a.Val); acc == big.Exact {
-		return 0
+		return true
 	}
 
 	// try rounding up a little
 	t.SetMode(big.AwayFromZero)
 	t.Set(&b.Val)
 	if _, acc := t.Int(&a.Val); acc == big.Exact {
-		return 0
+		return true
 	}
 
-	return -1
+	a.Ovf = false
+	return false
 }
 
 func (a *Mpint) Add(b *Mpint) {
diff --git a/test/fixedbugs/issue11371.go b/test/fixedbugs/issue11371.go
new file mode 100644
index 0000000000..b2d966fac8
--- /dev/null
+++ b/test/fixedbugs/issue11371.go
@@ -0,0 +1,17 @@
+// errorcheck
+
+// Copyright 2017 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Issue 11371 (cmd/compile: meaningless error message "truncated to
+// integer")
+
+package issue11371
+
+const a int = 1.1        // ERROR "constant 1.1 truncated to integer"
+const b int = 1e20       // ERROR "overflows int"
+const c int = 1 + 1e-100 // ERROR "constant truncated to integer"
+const d int = 1 - 1e-100 // ERROR "constant truncated to integer"
+const e int = 1.00000001 // ERROR "constant truncated to integer"
+const f int = 0.00000001 // ERROR "constant 1e-08 truncated to integer"
diff --git a/test/fixedbugs/issue13471.go b/test/fixedbugs/issue13471.go
index 81f034ba79..0bfed42616 100644
--- a/test/fixedbugs/issue13471.go
+++ b/test/fixedbugs/issue13471.go
@@ -9,17 +9,17 @@
 package main
 
 func main() {
-	const _ int64 = 1e646456992 // ERROR "1e\+646456992 overflows integer"
-	const _ int32 = 1e64645699  // ERROR "1e\+64645699 overflows integer"
-	const _ int16 = 1e6464569   // ERROR "1e\+6464569 overflows integer"
-	const _ int8 = 1e646456     // ERROR "1e\+646456 overflows integer"
-	const _ int = 1e64645       // ERROR "1e\+64645 overflows integer"
+	const _ int64 = 1e646456992 // ERROR "integer too large"
+	const _ int32 = 1e64645699  // ERROR "integer too large"
+	const _ int16 = 1e6464569   // ERROR "integer too large"
+	const _ int8 = 1e646456     // ERROR "integer too large"
+	const _ int = 1e64645       // ERROR "integer too large"
 
-	const _ uint64 = 1e646456992 // ERROR "1e\+646456992 overflows integer"
-	const _ uint32 = 1e64645699  // ERROR "1e\+64645699 overflows integer"
-	const _ uint16 = 1e6464569   // ERROR "1e\+6464569 overflows integer"
-	const _ uint8 = 1e646456     // ERROR "1e\+646456 overflows integer"
-	const _ uint = 1e64645       // ERROR "1e\+64645 overflows integer"
+	const _ uint64 = 1e646456992 // ERROR "integer too large"
+	const _ uint32 = 1e64645699  // ERROR "integer too large"
+	const _ uint16 = 1e6464569   // ERROR "integer too large"
+	const _ uint8 = 1e646456     // ERROR "integer too large"
+	const _ uint = 1e64645       // ERROR "integer too large"
 
-	const _ rune = 1e64645 // ERROR "1e\+64645 overflows integer"
+	const _ rune = 1e64645 // ERROR "integer too large"
 }
diff --git a/test/fixedbugs/issue13559.go b/test/fixedbugs/issue13559.go
index 4783c62f68..16de2a2e31 100644
--- a/test/fixedbugs/issue13559.go
+++ b/test/fixedbugs/issue13559.go
@@ -13,11 +13,11 @@ package p
 const _ int64 = 1e-10000 // ERROR "1e\-10000 truncated"
 
 const (
-	_ int64 = 1e10000000 // ERROR "1e\+10000000 overflows"
-	_ int64 = 1e1000000  // ERROR "1e\+1000000 overflows"
-	_ int64 = 1e100000   // ERROR "1e\+100000 overflows"
-	_ int64 = 1e10000    // ERROR "1e\+10000 overflows"
-	_ int64 = 1e1000     // ERROR "1e\+1000 overflows"
+	_ int64 = 1e10000000 // ERROR "integer too large"
+	_ int64 = 1e1000000  // ERROR "integer too large"
+	_ int64 = 1e100000   // ERROR "integer too large"
+	_ int64 = 1e10000    // ERROR "integer too large"
+	_ int64 = 1e1000     // ERROR "integer too large"
 	_ int64 = 1e100      // ERROR "10000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 overflows"
 	_ int64 = 1e10
 	_ int64 = 1e1
@@ -32,11 +32,11 @@ const (
 )
 
 const (
-	_ int64 = -1e10000000 // ERROR "\-1e\+10000000 overflows"
-	_ int64 = -1e1000000  // ERROR "\-1e\+1000000 overflows"
-	_ int64 = -1e100000   // ERROR "\-1e\+100000 overflows"
-	_ int64 = -1e10000    // ERROR "\-1e\+10000 overflows"
-	_ int64 = -1e1000     // ERROR "\-1e\+1000 overflows"
+	_ int64 = -1e10000000 // ERROR "integer too large"
+	_ int64 = -1e1000000  // ERROR "integer too large"
+	_ int64 = -1e100000   // ERROR "integer too large"
+	_ int64 = -1e10000    // ERROR "integer too large"
+	_ int64 = -1e1000     // ERROR "integer too large"
 	_ int64 = -1e100      // ERROR "\-10000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 overflows"
 	_ int64 = -1e10
 	_ int64 = -1e1
@@ -51,11 +51,11 @@ const (
 )
 
 const (
-	_ int64 = 1.23456789e10000000 // ERROR "1\.23457e\+10000000 overflows"
-	_ int64 = 1.23456789e1000000  // ERROR "1\.23457e\+1000000 overflows"
-	_ int64 = 1.23456789e100000   // ERROR "1\.23457e\+100000 overflows"
-	_ int64 = 1.23456789e10000    // ERROR "1\.23457e\+10000 overflows"
-	_ int64 = 1.23456789e1000     // ERROR "1\.23457e\+1000 overflows"
+	_ int64 = 1.23456789e10000000 // ERROR "integer too large"
+	_ int64 = 1.23456789e1000000  // ERROR "integer too large"
+	_ int64 = 1.23456789e100000   // ERROR "integer too large"
+	_ int64 = 1.23456789e10000    // ERROR "integer too large"
+	_ int64 = 1.23456789e1000     // ERROR "integer too large"
 	_ int64 = 1.23456789e100      // ERROR "12345678900000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 overflows"
 	_ int64 = 1.23456789e10
 	_ int64 = 1.23456789e1        // ERROR "12\.3457 truncated"
@@ -70,11 +70,11 @@ const (
 )
 
 const (
-	_ int64 = -1.23456789e10000000 // ERROR "\-1\.23457e\+10000000 overflows"
-	_ int64 = -1.23456789e1000000  // ERROR "\-1\.23457e\+1000000 overflows"
-	_ int64 = -1.23456789e100000   // ERROR "\-1\.23457e\+100000 overflows"
-	_ int64 = -1.23456789e10000    // ERROR "\-1\.23457e\+10000 overflows"
-	_ int64 = -1.23456789e1000     // ERROR "\-1\.23457e\+1000 overflows"
+	_ int64 = -1.23456789e10000000 // ERROR "integer too large"
+	_ int64 = -1.23456789e1000000  // ERROR "integer too large"
+	_ int64 = -1.23456789e100000   // ERROR "integer too large"
+	_ int64 = -1.23456789e10000    // ERROR "integer too large"
+	_ int64 = -1.23456789e1000     // ERROR "integer too large"
 	_ int64 = -1.23456789e100      // ERROR "\-12345678900000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 overflows"
 	_ int64 = -1.23456789e10
 	_ int64 = -1.23456789e1        // ERROR "\-12\.3457 truncated"