diff --git a/os_darwin.go b/os_darwin.go
index ed21a79..1c91671 100644
--- a/os_darwin.go
+++ b/os_darwin.go
@@ -1,3 +1,3 @@
 package goid
 
-type sigset uint32
\ No newline at end of file
+type sigset uint32
diff --git a/os_linux.go b/os_linux.go
index 2cff8c9..43bbadd 100644
--- a/os_linux.go
+++ b/os_linux.go
@@ -1,3 +1,3 @@
 package goid
 
-type sigset [2]uint32
\ No newline at end of file
+type sigset [2]uint32
diff --git a/p_m_go1.12.go b/p_m_go1.12.go
index 3d503ed..51a6cb1 100644
--- a/p_m_go1.12.go
+++ b/p_m_go1.12.go
@@ -11,22 +11,22 @@ type mutex struct {
 
 type p struct {
 	lock mutex
-	id int32 // Here is pid
+	id   int32 // Here is pid
 }
 
 type m struct {
-	g0      uintptr     // goroutine with scheduling stack
-	morebuf gobuf  // gobuf arg to morestack
-	divmod  uint32 // div/mod denominator for arm - known to liblink
+	g0      uintptr // goroutine with scheduling stack
+	morebuf gobuf   // gobuf arg to morestack
+	divmod  uint32  // div/mod denominator for arm - known to liblink
 
 	// Fields not known to debuggers.
-	procid        uint64       // for debuggers, but offset not hard-coded
-	gsignal       uintptr           // signal-handling g
-	goSigStack    gsignalStack // Go-allocated signal handling stack
-	sigmask       sigset // storage for saved signal mask
-	tls           [6]uintptr   // thread-local storage (for x86 extern register)
-	mstartfn      func()
-	curg          uintptr       // current running goroutine
-	caughtsig     uintptr // goroutine running during fatal signal
-	p             *p // attached p for executing go code (nil if not executing go code)
+	procid     uint64       // for debuggers, but offset not hard-coded
+	gsignal    uintptr      // signal-handling g
+	goSigStack gsignalStack // Go-allocated signal handling stack
+	sigmask    sigset       // storage for saved signal mask
+	tls        [6]uintptr   // thread-local storage (for x86 extern register)
+	mstartfn   func()
+	curg       uintptr // current running goroutine
+	caughtsig  uintptr // goroutine running during fatal signal
+	p          *p      // attached p for executing go code (nil if not executing go code)
 }
diff --git a/p_m_go1.13.go b/p_m_go1.13.go
index 4a51333..d9ffffb 100644
--- a/p_m_go1.13.go
+++ b/p_m_go1.13.go
@@ -14,18 +14,18 @@ type p struct {
 }
 
 type m struct {
-	g0      uintptr     // goroutine with scheduling stack
-	morebuf gobuf  // gobuf arg to morestack
-	divmod  uint32 // div/mod denominator for arm - known to liblink
+	g0      uintptr // goroutine with scheduling stack
+	morebuf gobuf   // gobuf arg to morestack
+	divmod  uint32  // div/mod denominator for arm - known to liblink
 
 	// Fields not known to debuggers.
-	procid        uint64       // for debuggers, but offset not hard-coded
-	gsignal       uintptr           // signal-handling g
-	goSigStack    gsignalStack // Go-allocated signal handling stack
-	sigmask       sigset // storage for saved signal mask
-	tls           [6]uintptr   // thread-local storage (for x86 extern register)
-	mstartfn      func()
-	curg          uintptr       // current running goroutine
-	caughtsig     uintptr // goroutine running during fatal signal
-	p             *p // attached p for executing go code (nil if not executing go code)
+	procid     uint64       // for debuggers, but offset not hard-coded
+	gsignal    uintptr      // signal-handling g
+	goSigStack gsignalStack // Go-allocated signal handling stack
+	sigmask    sigset       // storage for saved signal mask
+	tls        [6]uintptr   // thread-local storage (for x86 extern register)
+	mstartfn   func()
+	curg       uintptr // current running goroutine
+	caughtsig  uintptr // goroutine running during fatal signal
+	p          *p      // attached p for executing go code (nil if not executing go code)
 }
diff --git a/pid_go1.5_amd64.go b/pid_go1.5_amd64.go
index f57eb35..a57e797 100644
--- a/pid_go1.5_amd64.go
+++ b/pid_go1.5_amd64.go
@@ -18,14 +18,18 @@
 
 package goid
 
-import "unsafe"
+import (
+	"unsafe"
+)
+
+var _ = unsafe.Sizeof(0)
 
 //go:nosplit
-func getM() uintptr
+func getPid() uintptr
 
 //go:nosplit
 func GetPid() int {
-	return int((*m)(unsafe.Pointer(getM())).p.id)
+	return int(getPid())
 }
 
 //go:linkname procPin runtime.procPin
diff --git a/pid_go1.5_amd64.s b/pid_go1.5_amd64.s
index 132a291..06125e5 100644
--- a/pid_go1.5_amd64.s
+++ b/pid_go1.5_amd64.s
@@ -21,9 +21,11 @@
 #include "go_asm.h"
 #include "textflag.h"
 
-// func getM() int64
-TEXT ·getM(SB),NOSPLIT,$0-8
+// func getPid() int64
+TEXT ·getPid(SB),NOSPLIT,$0-8
 	MOVQ (TLS), R14
 	MOVQ g_m(R14), R13
+	MOVQ m_p(R13), R14
+	MOVL p_id(R14), R13
 	MOVQ R13, ret+0(FP)
 	RET
diff --git a/pid_go1.5_amd64_test.go b/pid_go1.5_amd64_test.go
index 17a6788..5f7ced7 100644
--- a/pid_go1.5_amd64_test.go
+++ b/pid_go1.5_amd64_test.go
@@ -10,7 +10,7 @@ import (
 func TestPid(t *testing.T) {
 	p1 := GetPid()
 	p2 := getTID()
-	if GetPid() != getTID() {
-		t.Fatalf("The result of GetPid %d is not equal to procPin %d!", p1, p2)
+	if p1 != p2 {
+		t.Fatalf("The result of GetPid %d procPin %d are not equal!", p1, p2)
 	}
 }