diff --git a/misc/cgo/test/cgo_test.go b/misc/cgo/test/cgo_test.go
index 4c7f676e0ba..ba2a89ef82f 100644
--- a/misc/cgo/test/cgo_test.go
+++ b/misc/cgo/test/cgo_test.go
@@ -90,6 +90,7 @@ func Test22906(t *testing.T)                 { test22906(t) }
 func Test24206(t *testing.T)                 { test24206(t) }
 func Test25143(t *testing.T)                 { test25143(t) }
 func Test23356(t *testing.T)                 { test23356(t) }
+func Test26066(t *testing.T)                 { test26066(t) }
 
 func BenchmarkCgoCall(b *testing.B)  { benchCgoCall(b) }
 func BenchmarkGoString(b *testing.B) { benchGoString(b) }
diff --git a/misc/cgo/test/issue26066.go b/misc/cgo/test/issue26066.go
new file mode 100644
index 00000000000..21028e7479b
--- /dev/null
+++ b/misc/cgo/test/issue26066.go
@@ -0,0 +1,19 @@
+// Copyright 2018 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.
+
+// Wrong type of constant with GCC 8 and newer.
+
+package cgotest
+
+// const unsigned long long int issue26066 = (const unsigned long long) -1;
+import "C"
+
+import "testing"
+
+func test26066(t *testing.T) {
+	var i = int64(C.issue26066)
+	if i != -1 {
+		t.Errorf("got %d, want -1", i)
+	}
+}
diff --git a/src/cmd/cgo/gcc.go b/src/cmd/cgo/gcc.go
index ae1df0d90f4..169894273be 100644
--- a/src/cmd/cgo/gcc.go
+++ b/src/cmd/cgo/gcc.go
@@ -586,7 +586,25 @@ func (p *Package) loadDWARF(f *File, names []*Name) {
 					}
 				}
 			case "fconst":
-				if i < len(floats) {
+				if i >= len(floats) {
+					break
+				}
+				switch base(types[i]).(type) {
+				case *dwarf.IntType, *dwarf.UintType:
+					// This has an integer type so it's
+					// not really a floating point
+					// constant. This can happen when the
+					// C compiler complains about using
+					// the value as an integer constant,
+					// but not as a general constant.
+					// Treat this as a variable of the
+					// appropriate type, not a constant,
+					// to get C-style type handling,
+					// avoiding the problem that C permits
+					// uint64(-1) but Go does not.
+					// See issue 26066.
+					n.Kind = "var"
+				default:
 					n.Const = fmt.Sprintf("%f", floats[i])
 				}
 			case "sconst":