diff --git a/src/cmd/6l/asm.c b/src/cmd/6l/asm.c
index 8c6bab8399..c3b2ba42f6 100644
--- a/src/cmd/6l/asm.c
+++ b/src/cmd/6l/asm.c
@@ -44,6 +44,7 @@
 char linuxdynld[] = "/lib64/ld-linux-x86-64.so.2";
 char freebsddynld[] = "/libexec/ld-elf.so.1";
 char openbsddynld[] = "/usr/libexec/ld.so";
+char netbsddynld[] = "/libexec/ld.elf_so";
 
 char	zeroes[32];
 
@@ -95,6 +96,7 @@ enum {
 	ElfStrPlt,
 	ElfStrGnuVersion,
 	ElfStrGnuVersionR,
+	ElfStrNoteNetbsdIdent,
 	NElfStr
 };
 
@@ -558,7 +560,7 @@ doelf(void)
 {
 	Sym *s, *shstrtab, *dynstr;
 
-	if(HEADTYPE != Hlinux && HEADTYPE != Hfreebsd && HEADTYPE != Hopenbsd)
+	if(HEADTYPE != Hlinux && HEADTYPE != Hfreebsd && HEADTYPE != Hopenbsd && HEADTYPE != Hnetbsd)
 		return;
 
 	/* predefine strings we need for section headers */
@@ -570,6 +572,8 @@ doelf(void)
 	elfstr[ElfStrText] = addstring(shstrtab, ".text");
 	elfstr[ElfStrData] = addstring(shstrtab, ".data");
 	elfstr[ElfStrBss] = addstring(shstrtab, ".bss");
+	if(HEADTYPE == Hnetbsd)
+		elfstr[ElfStrNoteNetbsdIdent] = addstring(shstrtab, ".note.netbsd.ident");
 	addstring(shstrtab, ".elfdata");
 	addstring(shstrtab, ".rodata");
 	addstring(shstrtab, ".gosymtab");
@@ -763,6 +767,7 @@ asmb(void)
 		break;
 	case Hlinux:
 	case Hfreebsd:
+	case Hnetbsd:
 	case Hopenbsd:
 		debug['8'] = 1;	/* 64-bit addresses */
 		/* index of elf text section; needed by asmelfsym, double-checked below */
@@ -798,6 +803,7 @@ asmb(void)
 			break;
 		case Hlinux:
 		case Hfreebsd:
+		case Hnetbsd:
 		case Hopenbsd:
 			symo = rnd(HEADR+segtext.len, INITRND)+segdata.filelen;
 			symo = rnd(symo, INITRND);
@@ -867,6 +873,7 @@ asmb(void)
 		break;
 	case Hlinux:
 	case Hfreebsd:
+	case Hnetbsd:
 	case Hopenbsd:
 		/* elf amd-64 */
 
@@ -910,6 +917,9 @@ asmb(void)
 				case Hfreebsd:
 					interpreter = freebsddynld;
 					break;
+				case Hnetbsd:
+					interpreter = netbsddynld;
+					break;
 				case Hopenbsd:
 					interpreter = openbsddynld;
 					break;
@@ -1076,6 +1086,8 @@ asmb(void)
 		eh->ident[EI_MAG3] = 'F';
 		if(HEADTYPE == Hfreebsd)
 			eh->ident[EI_OSABI] = ELFOSABI_FREEBSD;
+		else if(HEADTYPE == Hnetbsd)
+			eh->ident[EI_OSABI] = ELFOSABI_NETBSD;
 		else if(HEADTYPE == Hopenbsd)
 			eh->ident[EI_OSABI] = ELFOSABI_OPENBSD;
 		eh->ident[EI_CLASS] = ELFCLASS64;
diff --git a/src/cmd/6l/doc.go b/src/cmd/6l/doc.go
index b17642abbd..c18b0f29d5 100644
--- a/src/cmd/6l/doc.go
+++ b/src/cmd/6l/doc.go
@@ -31,6 +31,8 @@ Options new in this version:
 	Write Linux ELF binaries (default when $GOOS is linux)
 -Hfreebsd
 	Write FreeBSD ELF binaries (default when $GOOS is freebsd)
+-Hnetbsd
+	Write NetBSD ELF binaries (default when $GOOS is netbsd)
 -Hopenbsd
 	Write OpenBSD ELF binaries (default when $GOOS is openbsd)
 -Hwindows
diff --git a/src/cmd/6l/obj.c b/src/cmd/6l/obj.c
index 3ef8027fa9..de96468445 100644
--- a/src/cmd/6l/obj.c
+++ b/src/cmd/6l/obj.c
@@ -44,16 +44,17 @@ char*	thestring 	= "amd64";
 char*	paramspace	= "FP";
 
 Header headers[] = {
-   "plan9x32", Hplan9x32,
-   "plan9", Hplan9x64,
-   "elf", Helf,
-   "darwin", Hdarwin,
-   "linux", Hlinux,
-   "freebsd", Hfreebsd,
-   "openbsd", Hopenbsd,
-   "windows", Hwindows,
-   "windowsgui", Hwindows,
-   0, 0
+	"plan9x32", Hplan9x32,
+	"plan9", Hplan9x64,
+	"elf", Helf,
+	"darwin", Hdarwin,
+	"linux", Hlinux,
+	"freebsd", Hfreebsd,
+	"netbsd", Hnetbsd,
+	"openbsd", Hopenbsd,
+	"windows", Hwindows,
+	"windowsgui", Hwindows,
+	0, 0
 };
 
 /*
@@ -63,6 +64,7 @@ Header headers[] = {
  *	-Hdarwin -Tx -Rx		is apple MH-exec
  *	-Hlinux -Tx -Rx			is linux elf-exec
  *	-Hfreebsd -Tx -Rx		is FreeBSD elf-exec
+ *	-Hnetbsd -Tx -Rx		is NetBSD elf-exec
  *	-Hopenbsd -Tx -Rx		is OpenBSD elf-exec
  *	-Hwindows -Tx -Rx		is MS Windows PE32+
  *
@@ -197,6 +199,7 @@ main(int argc, char *argv[])
 		break;
 	case Hlinux:	/* elf64 executable */
 	case Hfreebsd:	/* freebsd */
+	case Hnetbsd:	/* netbsd */
 	case Hopenbsd:	/* openbsd */
 		/*
 		 * ELF uses TLS offset negative from FS.
diff --git a/src/cmd/6l/pass.c b/src/cmd/6l/pass.c
index d9e0b2fc1b..9f450d8fa4 100644
--- a/src/cmd/6l/pass.c
+++ b/src/cmd/6l/pass.c
@@ -295,7 +295,7 @@ patch(void)
 			}
 		}
 		if(HEADTYPE == Hlinux || HEADTYPE == Hfreebsd
-		|| HEADTYPE == Hopenbsd) {
+		|| HEADTYPE == Hopenbsd || HEADTYPE == Hnetbsd) {
 			// ELF uses FS instead of GS.
 			if(p->from.type == D_INDIR+D_GS)
 				p->from.type = D_INDIR+D_FS;
@@ -421,7 +421,7 @@ dostkoff(void)
 			p = appendp(p);	// load g into CX
 			p->as = AMOVQ;
 			if(HEADTYPE == Hlinux || HEADTYPE == Hfreebsd
-			|| HEADTYPE == Hopenbsd)	// ELF uses FS
+			|| HEADTYPE == Hopenbsd || HEADTYPE == Hnetbsd)	// ELF uses FS
 				p->from.type = D_INDIR+D_FS;
 			else
 				p->from.type = D_INDIR+D_GS;
diff --git a/src/cmd/8l/asm.c b/src/cmd/8l/asm.c
index 948d4889ca..3612c2bf2a 100644
--- a/src/cmd/8l/asm.c
+++ b/src/cmd/8l/asm.c
@@ -42,6 +42,7 @@
 char linuxdynld[] = "/lib/ld-linux.so.2";
 char freebsddynld[] = "/usr/libexec/ld-elf.so.1";
 char openbsddynld[] = "/usr/libexec/ld.so";
+char netbsddynld[] = "/usr/libexec/ld.elf_so";
 
 int32
 entryvalue(void)
@@ -969,6 +970,9 @@ asmb(void)
 				case Hfreebsd:
 					interpreter = freebsddynld;
 					break;
+				case Hnetbsd:
+					interpreter = netbsddynld;
+					break;
 				case Hopenbsd:
 					interpreter = openbsddynld;
 					break;
@@ -1140,6 +1144,9 @@ asmb(void)
 		case Hfreebsd:
 			eh->ident[EI_OSABI] = ELFOSABI_FREEBSD;
 			break;
+		case Hnetbsd:
+			eh->ident[EI_OSABI] = ELFOSABI_NETBSD;
+			break;
 		case Hopenbsd:
 			eh->ident[EI_OSABI] = ELFOSABI_OPENBSD;
 			break;
diff --git a/src/cmd/8l/doc.go b/src/cmd/8l/doc.go
index de877bb243..edd683823f 100644
--- a/src/cmd/8l/doc.go
+++ b/src/cmd/8l/doc.go
@@ -33,6 +33,8 @@ Options new in this version:
 	Write Linux ELF binaries (default when $GOOS is linux)
 -Hfreebsd
 	Write FreeBSD ELF binaries (default when $GOOS is freebsd)
+-Hnetbsd
+	Write NetBSD ELF binaries (default when $GOOS is netbsd)
 -Hopenbsd
 	Write OpenBSD ELF binaries (default when $GOOS is openbsd)
 -Hwindows
diff --git a/src/cmd/8l/obj.c b/src/cmd/8l/obj.c
index c2f409e91d..e17b667681 100644
--- a/src/cmd/8l/obj.c
+++ b/src/cmd/8l/obj.c
@@ -47,18 +47,19 @@ char	*noname		= "<none>";
 char	*thestring 	= "386";
 
 Header headers[] = {
-   "garbunix", Hgarbunix,
-   "unixcoff", Hunixcoff,
-   "plan9", Hplan9x32,
-   "msdoscom", Hmsdoscom,
-   "msdosexe", Hmsdosexe,
-   "darwin", Hdarwin,
-   "linux", Hlinux,
-   "freebsd", Hfreebsd,
-   "openbsd", Hopenbsd,
-   "windows", Hwindows,
-   "windowsgui", Hwindows,
-   0, 0
+	"garbunix", Hgarbunix,
+	"unixcoff", Hunixcoff,
+	"plan9", Hplan9x32,
+	"msdoscom", Hmsdoscom,
+	"msdosexe", Hmsdosexe,
+	"darwin", Hdarwin,
+	"linux", Hlinux,
+	"freebsd", Hfreebsd,
+	"netbsd", Hnetbsd,
+	"openbsd", Hopenbsd,
+	"windows", Hwindows,
+	"windowsgui", Hwindows,
+	0, 0
 };
 
 /*
@@ -70,6 +71,7 @@ Header headers[] = {
  *	-Hdarwin -Tx -Rx			is Apple Mach-O
  *	-Hlinux -Tx -Rx				is Linux ELF32
  *	-Hfreebsd -Tx -Rx			is FreeBSD ELF32
+ *	-Hnetbsd -Tx -Rx			is NetBSD ELF32
  *	-Hopenbsd -Tx -Rx			is OpenBSD ELF32
  *	-Hwindows -Tx -Rx			is MS Windows PE32
  */
@@ -225,6 +227,7 @@ main(int argc, char *argv[])
 		break;
 	case Hlinux:	/* elf32 executable */
 	case Hfreebsd:
+	case Hnetbsd:
 	case Hopenbsd:
 		/*
 		 * ELF uses TLS offsets negative from %gs.
diff --git a/src/cmd/cc/godefs.c b/src/cmd/cc/godefs.c
index 3ba979c8a3..4274c56265 100644
--- a/src/cmd/cc/godefs.c
+++ b/src/cmd/cc/godefs.c
@@ -124,11 +124,11 @@ Uconv(Fmt *fp)
 
 	if(s && *s) {
 		if(upper)
-			str[0] = toupper(*s);
+			str[0] = toupper((uchar)*s);
 		else
-			str[0] = tolower(*s);
+			str[0] = tolower((uchar)*s);
 		for(i = 1; i < STRINGSZ && s[i] != 0; i++)
-			str[i] = tolower(s[i]);
+			str[i] = tolower((uchar)s[i]);
 		str[i] = 0;
 	}
 
diff --git a/src/cmd/ld/lib.c b/src/cmd/ld/lib.c
index 7797d42ace..34440b8758 100644
--- a/src/cmd/ld/lib.c
+++ b/src/cmd/ld/lib.c
@@ -115,7 +115,7 @@ addlib(char *src, char *obj)
 		sprint(name, "");
 		i = 1;
 	} else
-	if(isalpha(histfrog[0]->name[1]) && histfrog[0]->name[2] == ':') {
+	if(isalpha((uchar)histfrog[0]->name[1]) && histfrog[0]->name[2] == ':') {
 		strcpy(name, histfrog[0]->name+1);
 		i = 1;
 	} else