diff --git a/src/cmd/gofmt/gofmt.go b/src/cmd/gofmt/gofmt.go
index 4bba44489d..d7a77a9682 100644
--- a/src/cmd/gofmt/gofmt.go
+++ b/src/cmd/gofmt/gofmt.go
@@ -335,66 +335,49 @@ func backupFile(filename string, data []byte, perm os.FileMode) (string, error)
 // alone.
 func normalizeNumbers(n ast.Node) bool {
 	lit, _ := n.(*ast.BasicLit)
-	if lit == nil {
+	if lit == nil || (lit.Kind != token.INT && lit.Kind != token.FLOAT && lit.Kind != token.IMAG) {
 		return true
 	}
 	if len(lit.Value) < 2 {
-		return false // only one digit - nothing to do
+		return false // only one digit (common case) - nothing to do
 	}
 	// len(lit.Value) >= 2
 
+	// We ignore lit.Kind because for lit.Kind == token.IMAG the literal may be an integer
+	// or floating-point value, decimal or not. Instead, just consider the literal pattern.
 	x := lit.Value
-	switch lit.Kind {
-	case token.INT:
-		switch x[:2] {
-		case "0X":
-			lit.Value = "0x" + x[2:]
-		case "0O":
-			lit.Value = "0o" + x[2:]
-		case "0B":
-			lit.Value = "0b" + x[2:]
+	switch x[:2] {
+	default:
+		// 0-prefix octal, decimal int, or float (possibly with 'i' suffix)
+		if i := strings.LastIndexByte(x, 'E'); i >= 0 {
+			x = x[:i] + "e" + x[i+1:]
+			break
 		}
-
-	case token.FLOAT:
-		switch lit.Value[:2] {
-		default:
-			if i := strings.LastIndexByte(x, 'E'); i >= 0 {
-				lit.Value = x[:i] + "e" + x[i+1:]
-			}
-		case "0x":
-			if i := strings.LastIndexByte(x, 'P'); i >= 0 {
-				lit.Value = x[:i] + "p" + x[i+1:]
-			}
-		case "0X":
-			if i := strings.LastIndexByte(x, 'P'); i >= 0 {
-				lit.Value = "0x" + x[2:i] + "p" + x[i+1:]
-			} else {
-				lit.Value = "0x" + x[2:]
-			}
-		}
-
-	case token.IMAG:
-		// Note that integer imaginary literals may contain
-		// any decimal digit even if they start with zero.
-		// Imaginary literals should always end in 'i' but be
-		// conservative and check anyway before proceeding.
-		if x[0] == '0' && x[len(x)-1] == 'i' && isDecimals(x[1:len(x)-1]) {
+		// remove leading 0's from integer (but not floating-point) imaginary literals
+		if x[len(x)-1] == 'i' && strings.IndexByte(x, '.') < 0 && strings.IndexByte(x, 'e') < 0 {
 			x = strings.TrimLeft(x, "0_")
 			if x == "i" {
 				x = "0i"
 			}
-			lit.Value = x
 		}
+	case "0X":
+		x = "0x" + x[2:]
+		fallthrough
+	case "0x":
+		// possibly a hexadecimal float
+		if i := strings.LastIndexByte(x, 'P'); i >= 0 {
+			x = x[:i] + "p" + x[i+1:]
+		}
+	case "0O":
+		x = "0o" + x[2:]
+	case "0o":
+		// nothing to do
+	case "0B":
+		x = "0b" + x[2:]
+	case "0b":
+		// nothing to do
 	}
 
+	lit.Value = x
 	return false
 }
-
-// isDecimals reports whether x consists entirely of decimal digits and underscores.
-func isDecimals(x string) bool {
-	i := 0
-	for i < len(x) && ('0' <= x[i] && x[i] <= '9' || x[i] == '_') {
-		i++
-	}
-	return i == len(x)
-}
diff --git a/src/cmd/gofmt/testdata/go2numbers.golden b/src/cmd/gofmt/testdata/go2numbers.golden
index abefcb6c58..0184aaa6ce 100644
--- a/src/cmd/gofmt/testdata/go2numbers.golden
+++ b/src/cmd/gofmt/testdata/go2numbers.golden
@@ -163,8 +163,24 @@ const (
 	_ = 0.i
 	_ = 123.i
 	_ = 0123.i
+	_ = 000123.i
+
+	_ = 0e0i
+	_ = 123e0i
+	_ = 0123e0i
+	_ = 000123e0i
 
 	_ = 0.e+1i
-	_ = 123.E-1_0i
+	_ = 123.e-1_0i
 	_ = 01_23.e123i
+	_ = 00_01_23.e123i
+
+	_ = 0b1010i
+	_ = 0b1010i
+	_ = 0o660i
+	_ = 0o660i
+	_ = 0xabcDEFi
+	_ = 0xabcDEFi
+	_ = 0xabcDEFp0i
+	_ = 0xabcDEFp0i
 )
diff --git a/src/cmd/gofmt/testdata/go2numbers.input b/src/cmd/gofmt/testdata/go2numbers.input
index 51a9f8eaf6..f3e7828d94 100644
--- a/src/cmd/gofmt/testdata/go2numbers.input
+++ b/src/cmd/gofmt/testdata/go2numbers.input
@@ -163,8 +163,24 @@ const (
 	_ = 0.i
 	_ = 123.i
 	_ = 0123.i
+	_ = 000123.i
+
+	_ = 0e0i
+	_ = 123e0i
+	_ = 0123E0i
+	_ = 000123E0i
 
 	_ = 0.e+1i
 	_ = 123.E-1_0i
 	_ = 01_23.e123i
+	_ = 00_01_23.e123i
+
+	_ = 0b1010i
+	_ = 0B1010i
+	_ = 0o660i
+	_ = 0O660i
+	_ = 0xabcDEFi
+	_ = 0XabcDEFi
+	_ = 0xabcDEFP0i
+	_ = 0XabcDEFp0i
 )
diff --git a/src/math/cmplx/cmath_test.go b/src/math/cmplx/cmath_test.go
index fbb49fdd5b..57ba76a767 100644
--- a/src/math/cmplx/cmath_test.go
+++ b/src/math/cmplx/cmath_test.go
@@ -222,7 +222,7 @@ var pow = []complex128{
 	(-2.499956739197529585028819e+00 + 1.759751724335650228957144e+00i),
 	(7.357094338218116311191939e+04 - 5.089973412479151648145882e+04i),
 	(1.320777296067768517259592e+01 - 3.165621914333901498921986e+01i),
-	(-3.123287828297300934072149e-07 - 1.9849567521490553032502223E-7i),
+	(-3.123287828297300934072149e-07 - 1.9849567521490553032502223e-7i),
 	(8.0622651468477229614813e+04 - 7.80028727944573092944363e+04i),
 	(-1.0268824572103165858577141e+00 - 4.716844738244989776610672e-01i),
 	(-4.35953819012244175753187e+01 + 2.2036445974645306917648585e+02i),