diff --git a/Makefile.linux b/Makefile.linux
index 505fa34ac..ec3299a30 100644
--- a/Makefile.linux
+++ b/Makefile.linux
@@ -32,6 +32,11 @@ CFLAGS += -Dstricmp=strcasecmp -Dstrnicmp=strncasecmp -DNEED_STRUPR
 LDFLAGS += -lz -ljpeg `sdl-config --libs` `pkg-config gtk+-2.0 --libs` $(FMOD_PREFIX)/lib/libfmodex${X64}.so
 NASMFLAGS += -f elf -DM_TARGET_LINUX
 
+ifdef VALGRIND
+  NOSTRIP = 1
+  NASMFLAGS += -DVALGRIND_AWARE
+endif
+
 SRCDIRS = src/ $(addprefix src/,g_doom/ g_heretic/ g_hexen/ g_raven/ g_shared/ g_strife/ oplsynth/ sound/ sdl/ textures/ thingdef/ xlat/ timidity/)
 VPATH = $(SRCDIRS)
 INCLUDES = $(addprefix -I,$(SRCDIRS))
@@ -71,6 +76,8 @@ else
   LDFLAGS += -Wl,-Map=$(ZDOOM).map
   ifndef NOSTRIP
     LDFLAGS += -s
+  else
+    CFLAGS += -g
   endif
   ZDOOMBIN = $(ZDOOM)
 endif
diff --git a/docs/rh-log.txt b/docs/rh-log.txt
index eb86a25ee..5fc4ef856 100644
--- a/docs/rh-log.txt
+++ b/docs/rh-log.txt
@@ -1,3 +1,7 @@
+June 7, 2008
+- Added self-modifying code notifications for Valgrind.
+  Build with make VALGRIND=1 to turn them on.
+
 June 6, 2008
 - Fixed: There was still an inventory bar check in FMugShot::GetFace() after
   separating it from DDoomStatusBar.
diff --git a/src/a.nas b/src/a.nas
index d4c4cf68f..cdcbd7f0f 100644
--- a/src/a.nas
+++ b/src/a.nas
@@ -3,6 +3,8 @@
 ; See the included license file "BUILDLIC.TXT" for license info.
 ; This file has been modified from Ken Silverman's original release
 
+%include "src/valgrind.inc"
+
 	SECTION .data
 
 %ifndef M_TARGET_LINUX
@@ -56,6 +58,7 @@ setvlinebpl_:
 	mov [fixchain1m+2], eax
 	mov [fixchain2ma+2], eax
 	mov [fixchain2mb+2], eax
+	selfmod fixchain1a, fixchain2mb+6
 	ret
 
 ; pass it log2(texheight)
@@ -87,6 +90,7 @@ setupvlineasm:
 	dec eax
 	mov dword [machvsh2+2], eax    ;(1<<shy)-1
 	mov dword [machvsh4+2], eax    ;(1<<shy)-1
+	selfmod premach3a, machvsh8+6
 	ret
 
 	SECTION .rtext	progbits alloc exec write align=64
@@ -250,6 +254,7 @@ machvsh12:	rol ebx, 88h                ;sh
 		add ebp, ebx
 
 		mov ecx, esi
+		selfmod beginvlineasm4, machvline4end+6
 		jmp short beginvlineasm4
 ALIGN 16
 beginvlineasm4:
@@ -323,6 +328,7 @@ setupmvlineasm:
 		mov byte [machmv14+2], cl
 		mov byte [machmv15+2], cl
 		mov byte [machmv16+2], cl
+		selfmod maskmach3a, machmv13+6
 		ret
 
 ALIGN 16
@@ -405,6 +411,7 @@ mvlineasm4:
 		mov ebp, [vplce+12]
 fixchain2ma:	sub edi, 320
 
+		selfmod beginmvlineasm4, machmv2+6
 		jmp short beginmvlineasm4
 ALIGN 16
 beginmvlineasm4:
@@ -529,3 +536,5 @@ mvcase1:	mov [edi], bl
 		jmp beginmvlineasm4
 ALIGN 16
 mvcase0:	jmp beginmvlineasm4
+
+align 16
diff --git a/src/tmap.nas b/src/tmap.nas
index 9d41223a4..e27b7ca15 100644
--- a/src/tmap.nas
+++ b/src/tmap.nas
@@ -33,6 +33,8 @@
 
 BITS 32
 
+%include "src/valgrind.inc"
+
 ; Segment/section definition macros. 
 
 	SECTION .data
@@ -176,6 +178,8 @@ R_SetSpanSource_ASM:
 	mov	[mspreade+2],ecx
 	mov	[mspreadf+2],ecx
 	mov	[mspreadg+2],ecx
+	
+	selfmod spreada, mspreadg+6
 
 	mov	[ds_cursource],ecx
 	ret
@@ -202,6 +206,8 @@ R_SetSpanColormap_ASM:
 	mov	[mspmape+2],ecx
 	mov	[mspmapf+2],ecx
 	mov	[mspmapg+2],ecx
+	
+	selfmod spmapa, mspmapg+6
 
 	mov	[ds_curcolormap],ecx
 	ret
@@ -275,10 +281,14 @@ R_SetSpanSize_ASM:
 	mov	[dmsy3+2],dl
 	mov	[dmsy4+2],dl
 	
+	selfmod dsy1, dmsm7+6
+	
 aret:	ret
 
 	SECTION .rtext	progbits alloc exec write align=64
 
+rtext_start:
+
 GLOBAL @R_DrawSpanP_ASM@0
 GLOBAL _R_DrawSpanP_ASM
 GLOBAL R_DrawSpanP_ASM
@@ -1731,6 +1741,7 @@ ac4p:	add		eax,320							; pitch
 ac4nil:	pop		edi
 		ret
 
+rtext_end:
 		align	16
 
 ;************************
@@ -1759,6 +1770,7 @@ R_SetupShadedCol:
 		mov		[s4fg2+3],eax
 		mov		[s4fg3+3],eax
 		mov		[s4fg4+3],eax
+		selfmod s4cm1, s4fg4+7
 .cdone	ret
 
 GLOBAL	R_SetupAddCol
@@ -1790,6 +1802,7 @@ R_SetupAddCol:
 		mov		[a4bg2+3],eax
 		mov		[a4bg3+3],eax
 		mov		[a4bg4+3],eax
+		selfmod a4cm1, a4bg4+7
 .dbdone	ret
 
 GLOBAL	R_SetupAddClampCol
@@ -1821,6 +1834,7 @@ R_SetupAddClampCol:
 		mov		[ac4bg2+3],eax
 		mov		[ac4bg3+3],eax
 		mov		[ac4bg4+3],eax
+		selfmod ac4cm1, ac4bg4+7
 .dbdone	ret
 
 EXTERN setvlinebpl_
@@ -1847,5 +1861,6 @@ _ASM_PatchPitch:
 		mov		[s4p2+2],ecx
 		inc		ecx
 		mov		[s4p3+2],ecx
+		selfmod rtext_start, rtext_end
 		call	setpitch3
 		jmp		setvlinebpl_
diff --git a/src/tmap2.nas b/src/tmap2.nas
index ef0b84d1e..da95a3d85 100644
--- a/src/tmap2.nas
+++ b/src/tmap2.nas
@@ -37,6 +37,8 @@
 
 BITS 32
 
+%include "src/valgrind.inc"
+
 %define SPACEFILLER4	(0x44444444)
 
 %ifndef M_TARGET_LINUX
@@ -160,6 +162,7 @@ R_SetTiltedSpanSource_ASM:
 	mov	[fetch9+3],ecx
 	mov	[fetch10+3],ecx
 	mov	[ds_curtiltedsource],ecx
+	selfmod rtext_start, rtext_end
 	ret
 	
 GLOBAL	SetTiltedSpanSize
@@ -209,10 +212,14 @@ SetTiltedSpanSize:
 	mov	[m9+2],eax
 	mov	[m10+2],eax
 	
+	selfmod rtext_start, rtext_end
+	
 	ret
 
 	SECTION .rtext	progbits alloc exec write align=64
 
+rtext_start:
+
 GLOBAL	R_DrawTiltedPlane_ASM
 GLOBAL	@R_DrawTiltedPlane_ASM@8
 
@@ -619,3 +626,5 @@ fetch10	mov	al,[ebp+esi+SPACEFILLER4]
 	pop	esi
 	pop	ebx
 	ret
+
+rtext_end:
diff --git a/src/tmap3.nas b/src/tmap3.nas
index a77a99ba9..05b68aaeb 100644
--- a/src/tmap3.nas
+++ b/src/tmap3.nas
@@ -1,3 +1,5 @@
+%include "src/valgrind.inc"
+
 %ifdef M_TARGET_WATCOM
   SEGMENT DATA PUBLIC ALIGN=16 CLASS=DATA USE32
   SEGMENT DATA
@@ -57,6 +59,7 @@ setpitch3:
 	mov	[vltpitcha+2],eax
 	mov	[vlt1pitch1+2], eax
 	mov	[vlt1pitch2+2], eax
+	selfmod vltpitch, vlt1pitch2+6
 	ret
 
 ALIGN 16
@@ -74,6 +77,7 @@ setupvlinetallasm:
 	mov	[preshift+2], cl
 	mov	[shift11+2], cl
 	mov	[shift12+2], cl
+	selfmod shifter1, shift12+6
 	ret
 
 	SECTION .rtext	progbits alloc exec write align=64
@@ -126,6 +130,7 @@ vlinetallasm4:
 	mov	ecx, [vplce+4]
 	mov	esi, [vplce+8]
 	mov	eax, [vplce+12]
+	selfmod loopit, vltpitch
 	jmp	loopit
 
 ALIGN	16
@@ -217,6 +222,7 @@ vlinetallasmathlon4:
 	mov	ecx, [vplce+4]
 	mov	esi, [vplce+8]
 	mov	eax, [vplce+12]
+	selfmod loopita, vltpitcha
 	jmp	loopita
 
 ; Unfortunately, this code has not been carefully analyzed to determine
diff --git a/src/valgrind.inc b/src/valgrind.inc
new file mode 100644
index 000000000..729fe89bc
--- /dev/null
+++ b/src/valgrind.inc
@@ -0,0 +1,31 @@
+%ifdef VALGRIND_AWARE
+
+%define VG_USERREQ__DISCARD_TRANSLATIONS 0x1002
+
+%macro selfmod 2
+		pusha
+		sub		esp,6*4
+		mov		dword [esp],    VG_USERREQ__DISCARD_TRANSLATIONS
+		mov		dword [esp+4],  %1
+		mov		dword [esp+8],  %2 - %1
+		mov		dword [esp+12], 0
+		mov		dword [esp+16], 0
+		mov		dword [esp+20], 0
+		mov		eax, esp
+		; special instruction preamble
+		rol		edi, 3
+		rol		edi, 13
+		rol		edi, 29
+		rol		edi, 19
+		xchg	ebx, ebx
+		; restore state
+		add		esp,6*4
+		popa
+%endmacro
+
+%else
+
+%macro selfmod 2
+%endmacro
+
+%endif