diff --git a/.gitignore b/.gitignore
index fcbdfcd52..652d8f18f 100644
--- a/.gitignore
+++ b/.gitignore
@@ -57,3 +57,4 @@ bin/execrate
 *.project
 *.core
 core
+**/#*#
diff --git a/src/cmd/builtin/features/pty b/src/cmd/builtin/features/pty
index dc6a7104a..893778871 100755
--- a/src/cmd/builtin/features/pty
+++ b/src/cmd/builtin/features/pty
@@ -54,7 +54,9 @@ tst - output{
 			}
 		return 0;
 	}
-}end  
+}end fail{
+	echo '#error The output block in src/cmd/builtin/features/pty failed to compile'
+}end
 
 extern	_getpty		char*		(int*, int, mode_t, int)
 extern	openpty		int		(int*, int*, char*, struct termios*, struct winsize*)
diff --git a/src/lib/libast/features/common b/src/lib/libast/features/common
index 8f5e305f7..5443fa341 100644
--- a/src/lib/libast/features/common
+++ b/src/lib/libast/features/common
@@ -352,6 +352,8 @@ tst	- output{
 		printf("\n");
 		return 0;
 	}
+}end fail{
+	echo '#error Output block #2 in src/lib/libast/features/common failed to compile'
 }end
 
 tst	- -DN=1 - -DN=0 output{
diff --git a/src/lib/libast/features/float b/src/lib/libast/features/float
index d927bc167..ce1ec7b83 100644
--- a/src/lib/libast/features/float
+++ b/src/lib/libast/features/float
@@ -894,6 +894,8 @@ tst	- note{ missing floating point limits }end output{
 
 		return 0;
 	}
+}end fail{
+	echo '#error Output block #1 in src/lib/libast/features/float failed to compile'
 }end
 
 tst	- note{ double exponent bitfoolery }end output{
@@ -928,6 +930,8 @@ tst	- note{ double exponent bitfoolery }end output{
 			}
 		return 0;
 	}
+}end fail{
+	echo '#error Output block #2 in src/lib/libast/features/float failed to compile'
 }end
 
 tst	- note{ long double exponent bitfoolery }end output{
@@ -962,6 +966,8 @@ tst	- note{ long double exponent bitfoolery }end output{
 			}
 		return 0;
 	}
+}end fail{
+	echo '#error Output block #3 in src/lib/libast/features/float failed to compile'
 }end
 
 tst	- -DN=1 - -DN=2 note{ _ast_fltmax_t maximum integral type }end output{
diff --git a/src/lib/libast/features/lib b/src/lib/libast/features/lib
index 4c1e81d64..4522a5cbe 100644
--- a/src/lib/libast/features/lib
+++ b/src/lib/libast/features/lib
@@ -699,6 +699,8 @@ tst	- output{
 		return 0;
 	}
 
+}end fail{
+	echo '#error The output block in src/lib/libast/features/lib failed to compile'
 }end
 
 tst	no64 -D_LARGEFILE64_SOURCE note{ largefile 64 broken }end execute{
diff --git a/src/lib/libast/features/sfio b/src/lib/libast/features/sfio
index 2d29706ef..d12c398fe 100644
--- a/src/lib/libast/features/sfio
+++ b/src/lib/libast/features/sfio
@@ -14,6 +14,8 @@ tst	- note{ number of bits in pointer }end output{
 		printf("#define _ptr_bits	%d\n", sizeof(char*) * 8);
 		return 0;
 	}
+}end fail{
+	echo '#error The output block in src/lib/libast/features/sfio failed to compile'
 }end
 
 tst	tmp_rmfail note{ open files cannot be removed }end execute{
diff --git a/src/lib/libast/features/sizeof b/src/lib/libast/features/sizeof
index 06c8707a1..06080eb12 100644
--- a/src/lib/libast/features/sizeof
+++ b/src/lib/libast/features/sizeof
@@ -10,4 +10,6 @@ tst	- note{ sizeof(integral-type) }end output{
 		printf("#define _ast_sizeof_intmax_t	%d\n", sizeof(_ast_intmax_t));
 		return 0;
 	}
+}end fail{
+	echo '#error The output block in src/lib/libast/features/sizeof failed to compile'
 }end
diff --git a/src/lib/libast/include/vmalloc.h b/src/lib/libast/include/vmalloc.h
index f607b719f..161ea2cec 100644
--- a/src/lib/libast/include/vmalloc.h
+++ b/src/lib/libast/include/vmalloc.h
@@ -136,7 +136,9 @@ extern Vmethod_t*	Vmprofile;	/* profiling memory usage	*/
 
 extern Vmdisc_t*	Vmdcsystem;	/* get memory from the OS	*/
 extern Vmdisc_t*	Vmdcheap;	/* get memory from Vmheap	*/
+#if _mem_sbrk
 extern Vmdisc_t*	Vmdcsbrk;	/* like Vmdcsystem - legacy use	*/
+#endif
 
 extern Vmalloc_t	_Vmheap;	/* heap region - use with care! */
 extern Vmalloc_t*	Vmheap;		/* = &_Vmheap - safe to use	*/
diff --git a/src/lib/libast/vmalloc/vmbest.c b/src/lib/libast/vmalloc/vmbest.c
index 5b65ddace..b689af643 100644
--- a/src/lib/libast/vmalloc/vmbest.c
+++ b/src/lib/libast/vmalloc/vmbest.c
@@ -1265,10 +1265,13 @@ static Void_t* mmapmem(Void_t* caddr, size_t csize, size_t nsize, Mmdisc_t* mmdc
 		}
 	}
 	else if(nsize == 0)
-	{	Vmuchar_t	*addr = (Vmuchar_t*)sbrk(0);
+	{
+#if _mem_sbrk
+		Vmuchar_t	*addr = (Vmuchar_t*)sbrk(0);
 		if(addr < (Vmuchar_t*)caddr ) /* in sbrk space */
 			return NIL(Void_t*);
 		else
+#endif
 		{	(void)munmap(caddr, csize);
 			return caddr;
 		}
@@ -1385,7 +1388,9 @@ __DEFINE__(Vmalloc_t*, Vmheap, &_Vmheap);
 __DEFINE__(Vmalloc_t*, Vmregion, &_Vmheap);
 __DEFINE__(Vmethod_t*, Vmbest, &_Vmbest);
 __DEFINE__(Vmdisc_t*,  Vmdcsystem, (Vmdisc_t*)(&_Vmdcsystem) );
+#if _mem_sbrk
 __DEFINE__(Vmdisc_t*,  Vmdcsbrk, (Vmdisc_t*)(&_Vmdcsystem) );
+#endif
 
 #ifdef NoF
 NoF(vmbest)