diff --git a/graph/internal/set/same.go b/graph/internal/set/same.go
index baa43979..75718e0b 100644
--- a/graph/internal/set/same.go
+++ b/graph/internal/set/same.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//+build !appengine
+// +build !appengine
 
 package set
 
diff --git a/graph/internal/set/same_appengine.go b/graph/internal/set/same_appengine.go
index 5386550a..cd52a8f6 100644
--- a/graph/internal/set/same_appengine.go
+++ b/graph/internal/set/same_appengine.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//+build appengine
+// +build appengine
 
 package set
 
diff --git a/graph/topo/non_tomita_choice.go b/graph/topo/non_tomita_choice.go
index f4fcfd08..36171d6f 100644
--- a/graph/topo/non_tomita_choice.go
+++ b/graph/topo/non_tomita_choice.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//+build !tomita
+// +build !tomita
 
 package topo
 
diff --git a/graph/topo/tomita_choice.go b/graph/topo/tomita_choice.go
index 7d6efb34..f85a0d6c 100644
--- a/graph/topo/tomita_choice.go
+++ b/graph/topo/tomita_choice.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//+build tomita
+// +build tomita
 
 package topo
 
diff --git a/internal/asm/c128/stubs_amd64.go b/internal/asm/c128/stubs_amd64.go
index c03df58b..68c92d20 100644
--- a/internal/asm/c128/stubs_amd64.go
+++ b/internal/asm/c128/stubs_amd64.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//+build !noasm,!appengine
+// +build !noasm,!appengine
 
 package c128
 
diff --git a/internal/asm/c128/stubs_noasm.go b/internal/asm/c128/stubs_noasm.go
index 92abe0d9..47930bb4 100644
--- a/internal/asm/c128/stubs_noasm.go
+++ b/internal/asm/c128/stubs_noasm.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//+build !amd64 noasm appengine
+// +build !amd64 noasm appengine
 
 package c128
 
diff --git a/internal/asm/c64/stubs_amd64.go b/internal/asm/c64/stubs_amd64.go
index d64cdb2b..636c64af 100644
--- a/internal/asm/c64/stubs_amd64.go
+++ b/internal/asm/c64/stubs_amd64.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//+build !noasm,!appengine
+// +build !noasm,!appengine
 
 package c64
 
diff --git a/internal/asm/c64/stubs_noasm.go b/internal/asm/c64/stubs_noasm.go
index c434dd16..5ef7a2eb 100644
--- a/internal/asm/c64/stubs_noasm.go
+++ b/internal/asm/c64/stubs_noasm.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//+build !amd64 noasm appengine
+// +build !amd64 noasm appengine
 
 package c64
 
diff --git a/internal/asm/f32/ge_amd64.go b/internal/asm/f32/ge_amd64.go
index e20cefde..f466d8e0 100644
--- a/internal/asm/f32/ge_amd64.go
+++ b/internal/asm/f32/ge_amd64.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//+build !noasm,!appengine
+// +build !noasm,!appengine
 
 package f32
 
diff --git a/internal/asm/f32/ge_noasm.go b/internal/asm/f32/ge_noasm.go
index 0b7d8fdc..cd701a39 100644
--- a/internal/asm/f32/ge_noasm.go
+++ b/internal/asm/f32/ge_noasm.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//+build !amd64 noasm appengine
+// +build !amd64 noasm appengine
 
 package f32
 
diff --git a/internal/asm/f32/stubs_amd64.go b/internal/asm/f32/stubs_amd64.go
index 111f99a9..794d00f7 100644
--- a/internal/asm/f32/stubs_amd64.go
+++ b/internal/asm/f32/stubs_amd64.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//+build !noasm,!appengine
+// +build !noasm,!appengine
 
 package f32
 
diff --git a/internal/asm/f32/stubs_noasm.go b/internal/asm/f32/stubs_noasm.go
index 55e21e4a..6f0aeccd 100644
--- a/internal/asm/f32/stubs_noasm.go
+++ b/internal/asm/f32/stubs_noasm.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//+build !amd64 noasm appengine
+// +build !amd64 noasm appengine
 
 package f32
 
diff --git a/internal/asm/f64/axpy.go b/internal/asm/f64/axpy.go
index 00b874d1..b1668e75 100644
--- a/internal/asm/f64/axpy.go
+++ b/internal/asm/f64/axpy.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//+build !amd64 noasm appengine
+// +build !amd64 noasm appengine
 
 package f64
 
diff --git a/internal/asm/f64/dot.go b/internal/asm/f64/dot.go
index 98a17605..909509a2 100644
--- a/internal/asm/f64/dot.go
+++ b/internal/asm/f64/dot.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//+build !amd64 noasm appengine
+// +build !amd64 noasm appengine
 
 package f64
 
diff --git a/internal/asm/f64/ge_amd64.go b/internal/asm/f64/ge_amd64.go
index 12dd3232..dd27779a 100644
--- a/internal/asm/f64/ge_amd64.go
+++ b/internal/asm/f64/ge_amd64.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//+build !noasm,!appengine
+// +build !noasm,!appengine
 
 package f64
 
diff --git a/internal/asm/f64/ge_noasm.go b/internal/asm/f64/ge_noasm.go
index d180ae85..2150b87f 100644
--- a/internal/asm/f64/ge_noasm.go
+++ b/internal/asm/f64/ge_noasm.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//+build !amd64 noasm appengine
+// +build !amd64 noasm appengine
 
 package f64
 
diff --git a/internal/asm/f64/scal.go b/internal/asm/f64/scal.go
index 9d11a102..745dd5eb 100644
--- a/internal/asm/f64/scal.go
+++ b/internal/asm/f64/scal.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//+build !amd64 noasm appengine
+// +build !amd64 noasm appengine
 
 package f64
 
diff --git a/internal/asm/f64/stubs_amd64.go b/internal/asm/f64/stubs_amd64.go
index f1c532ad..6116d58b 100644
--- a/internal/asm/f64/stubs_amd64.go
+++ b/internal/asm/f64/stubs_amd64.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//+build !noasm,!appengine
+// +build !noasm,!appengine
 
 package f64
 
diff --git a/internal/asm/f64/stubs_noasm.go b/internal/asm/f64/stubs_noasm.go
index 2d0b0ce9..b0be9406 100644
--- a/internal/asm/f64/stubs_noasm.go
+++ b/internal/asm/f64/stubs_noasm.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//+build !amd64 noasm appengine
+// +build !amd64 noasm appengine
 
 package f64
 
diff --git a/internal/math32/sqrt.go b/internal/math32/sqrt.go
index ba4747a6..36074122 100644
--- a/internal/math32/sqrt.go
+++ b/internal/math32/sqrt.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//+build !amd64 noasm appengine
+// +build !amd64 noasm appengine
 
 package math32
 
diff --git a/internal/math32/sqrt_amd64.go b/internal/math32/sqrt_amd64.go
index 48602662..633f933a 100644
--- a/internal/math32/sqrt_amd64.go
+++ b/internal/math32/sqrt_amd64.go
@@ -6,7 +6,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//+build !noasm,!appengine
+// +build !noasm,!appengine
 
 package math32
 
diff --git a/mat/cblas_test.go b/mat/cblas_test.go
index a1a5c147..a5036f2b 100644
--- a/mat/cblas_test.go
+++ b/mat/cblas_test.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//+build cblas
+// +build cblas
 
 package mat
 
diff --git a/mat/index_bound_checks.go b/mat/index_bound_checks.go
index bb1fe5b6..3dd5cfc3 100644
--- a/mat/index_bound_checks.go
+++ b/mat/index_bound_checks.go
@@ -4,7 +4,7 @@
 
 // This file must be kept in sync with index_no_bound_checks.go.
 
-//+build bounds
+// +build bounds
 
 package mat
 
diff --git a/mat/index_no_bound_checks.go b/mat/index_no_bound_checks.go
index 947be6c2..9a49a7f5 100644
--- a/mat/index_no_bound_checks.go
+++ b/mat/index_no_bound_checks.go
@@ -4,7 +4,7 @@
 
 // This file must be kept in sync with index_bound_checks.go.
 
-//+build !bounds
+// +build !bounds
 
 package mat
 
diff --git a/mat/offset.go b/mat/offset.go
index 7341cc0c..03dd07d9 100644
--- a/mat/offset.go
+++ b/mat/offset.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//+build !appengine
+// +build !appengine
 
 package mat
 
diff --git a/mat/offset_appengine.go b/mat/offset_appengine.go
index b731786d..16b8f796 100644
--- a/mat/offset_appengine.go
+++ b/mat/offset_appengine.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//+build appengine
+// +build appengine
 
 package mat