diff --git a/libguile/posix.c b/libguile/posix.c
index f9ce0adc4..6dd0551f7 100644
--- a/libguile/posix.c
+++ b/libguile/posix.c
@@ -928,8 +928,7 @@ environ_list_to_c (SCM envlist, int arg, const char *proc)
       int len;
       char *src;
 
-      SCM_ASSERT (SCM_NIMP (SCM_CAR (envlist))
-		  && SCM_ROSTRINGP (SCM_CAR (envlist)),
+      SCM_ASSERT (SCM_ROSTRINGP (SCM_CAR (envlist)),
 		  envlist, arg, proc);
       len = 1 + SCM_ROLENGTH (SCM_CAR (envlist));
       result[i] = malloc ((long) len);
diff --git a/libguile/print.c b/libguile/print.c
index 31f719328..01873af39 100644
--- a/libguile/print.c
+++ b/libguile/print.c
@@ -888,10 +888,9 @@ circref:
 int
 scm_valid_oport_value_p	(SCM val)
 {
-  return (SCM_NIMP (val)
-	  && (SCM_OPOUTPORTP (val)
-	      || (SCM_PORT_WITH_PS_P (val)
-		  && SCM_OPOUTPORTP (SCM_PORT_WITH_PS_PORT (val)))));
+  return (SCM_OPOUTPORTP (val)
+          || (SCM_PORT_WITH_PS_P (val)
+              && SCM_OPOUTPORTP (SCM_PORT_WITH_PS_PORT (val))));
 }
 
 /* SCM_GPROC(s_write, "write", 1, 1, 0, scm_write, g_write); */
@@ -1022,13 +1021,10 @@ GUILE_PROC (scm_get_print_state, "get-print-state", 1, 0, 0,
 "")
 #define FUNC_NAME s_scm_get_print_state
 {
-  if (SCM_NIMP (port))
-    {
-      if (SCM_PORT_WITH_PS_P (port))
-	return SCM_PORT_WITH_PS_PS (port);
-      if (SCM_OUTPORTP (port))
-	return SCM_BOOL_F;
-    }
+  if (SCM_PORT_WITH_PS_P (port))
+    return SCM_PORT_WITH_PS_PS (port);
+  if (SCM_OUTPORTP (port))
+    return SCM_BOOL_F;
   RETURN_SCM_WTA (1,port);
 }
 #undef FUNC_NAME
diff --git a/libguile/ramap.c b/libguile/ramap.c
index 62b9b93ec..14c68d480 100644
--- a/libguile/ramap.c
+++ b/libguile/ramap.c
@@ -182,8 +182,7 @@ scm_ra_matchp (SCM ra0, SCM ras)
 	bas0 = SCM_ARRAY_BASE (ra0);
 	break;
       }
-  while SCM_NIMP
-    (ras)
+  while (SCM_NIMP (ras))
       {
 	ra1 = SCM_CAR (ras);
 	if (SCM_IMP (ra1))
diff --git a/libguile/random.c b/libguile/random.c
index 2c424c5d1..372ff61e0 100644
--- a/libguile/random.c
+++ b/libguile/random.c
@@ -466,9 +466,7 @@ GUILE_PROC (scm_random_solid_sphere_x, "random:solid-sphere!", 1, 1, 0,
 "")
 #define FUNC_NAME s_scm_random_solid_sphere_x
 {
-  SCM_ASSERT (SCM_NIMP (v)
-	      && (SCM_VECTORP (v) || SCM_TYP7 (v) == scm_tc7_dvect),
-	      v, SCM_ARG1, FUNC_NAME);
+  SCM_VALIDATE_VECTOR_OR_DVECTOR(1,v);
   if (SCM_UNBNDP (state))
     state = SCM_CDR (scm_var_random_state);
   SCM_VALIDATE_RSTATE(2,state);
@@ -486,9 +484,7 @@ GUILE_PROC (scm_random_hollow_sphere_x, "random:hollow-sphere!", 1, 1, 0,
 "")
 #define FUNC_NAME s_scm_random_hollow_sphere_x
 {
-  SCM_ASSERT (SCM_NIMP (v)
-	      && (SCM_VECTORP (v) || SCM_TYP7 (v) == scm_tc7_dvect),
-	      v, SCM_ARG1, FUNC_NAME);
+  SCM_VALIDATE_VECTOR_OR_DVECTOR(1,v);
   if (SCM_UNBNDP (state))
     state = SCM_CDR (scm_var_random_state);
   SCM_VALIDATE_RSTATE(2,state);
@@ -505,9 +501,7 @@ GUILE_PROC (scm_random_normal_vector_x, "random:normal-vector!", 1, 1, 0,
 #define FUNC_NAME s_scm_random_normal_vector_x
 {
   int n;
-  SCM_ASSERT (SCM_NIMP (v)
-	      && (SCM_VECTORP (v) || SCM_TYP7 (v) == scm_tc7_dvect),
-	      v, SCM_ARG1, FUNC_NAME);
+  SCM_VALIDATE_VECTOR_OR_DVECTOR(1,v);
   if (SCM_UNBNDP (state))
     state = SCM_CDR (scm_var_random_state);
   SCM_VALIDATE_RSTATE(2,state);
diff --git a/libguile/scm_validate.h b/libguile/scm_validate.h
index 3af1c9789..d67f2b780 100644
--- a/libguile/scm_validate.h
+++ b/libguile/scm_validate.h
@@ -1,4 +1,4 @@
-/* $Id: scm_validate.h,v 1.8 1999-12-19 01:04:36 gjb Exp $ */
+/* $Id: scm_validate.h,v 1.9 2000-01-05 16:16:57 gjb Exp $ */
 /*	Copyright (C) 1999 Free Software Foundation, Inc.
  * 
  * This program is free software; you can redistribute it and/or modify
@@ -264,6 +264,11 @@
 
 #define SCM_VALIDATE_VECTOR(pos,v) SCM_MAKE_VALIDATE(pos,v,VECTORP)
 
+#define SCM_VALIDATE_VECTOR_OR_DVECTOR(pos,v) \
+  do { SCM_ASSERT ((SCM_VECTORP (v) ||  \
+                    (SCM_NIMP (v) && SCM_TYP7 (v) == scm_tc7_dvect)), \
+                   v, pos, FUNC_NAME); } while (0) 
+
 #define SCM_VALIDATE_STRUCT(pos,v) SCM_MAKE_VALIDATE(pos,v,STRUCTP)
 
 #define SCM_VALIDATE_VTABLE(pos,v) \
diff --git a/libguile/stacks.c b/libguile/stacks.c
index 7cf4d55c9..5533dce58 100644
--- a/libguile/stacks.c
+++ b/libguile/stacks.c
@@ -364,15 +364,13 @@ narrow_stack (SCM stack,int inner,SCM inner_key,int outer,SCM outer_key)
       for (i = 0; inner; ++i, --inner)
 	{
 	  SCM m = s->frames[i].source;
-	  if (SCM_NIMP (m)
-	      && SCM_MEMOIZEDP (m)
+	  if (   SCM_MEMOIZEDP (m)
 	      && SCM_NIMP (SCM_MEMOIZED_ENV (m))
 	      && SCM_FALSEP (scm_system_module_env_p (SCM_MEMOIZED_ENV (m))))
 	    {
 	      /* Back up in order to include any non-source frames */
 	      while (i > 0
-		     && !((SCM_NIMP (m = s->frames[i - 1].source)
-			   && SCM_MEMOIZEDP (m))
+		     && !((m = s->frames[i - 1].source, SCM_MEMOIZEDP (m))
 			  || (SCM_NIMP (m = s->frames[i - 1].proc)
 			      && SCM_NFALSEP (scm_procedure_p (m))
 			      && SCM_NFALSEP (scm_procedure_property
diff --git a/libguile/strings.c b/libguile/strings.c
index 1a155b059..ed7d07351 100644
--- a/libguile/strings.c
+++ b/libguile/strings.c
@@ -333,8 +333,7 @@ GUILE_PROC(scm_string_append, "string-append", 0, 0, 1,
   register long i = 0;
   register SCM l, s;
   register unsigned char *data;
-  for (l = args;SCM_NIMP (l);) {
-    SCM_ASSERT (SCM_CONSP (l), l, SCM_ARGn, FUNC_NAME);
+  for (l = args;SCM_CONSP (l);) {
     s = SCM_CAR (l);
     SCM_VALIDATE_ROSTRING(SCM_ARGn,s);
     i += SCM_ROLENGTH (s);
diff --git a/libguile/symbols.c b/libguile/symbols.c
index cd43b625d..27dd69446 100644
--- a/libguile/symbols.c
+++ b/libguile/symbols.c
@@ -827,8 +827,7 @@ prefix for the new symbol's name.  The default prefix is @code{%%gensym}.")
       goto skip_test;
     }
   else
-    SCM_ASSERT (SCM_NIMP (obarray)
-		&& (SCM_VECTORP (obarray) || SCM_WVECTP (obarray)),
+    SCM_ASSERT ((SCM_VECTORP (obarray) || SCM_WVECTP (obarray)),
 		obarray,
 		SCM_ARG2,
 		FUNC_NAME);
diff --git a/libguile/unif.c b/libguile/unif.c
index 875f60f75..7d6c51ddd 100644
--- a/libguile/unif.c
+++ b/libguile/unif.c
@@ -305,15 +305,13 @@ loop:
       return nprot || SCM_BOOL(SCM_INUMP(prot) && SCM_INUM(prot)<=0);
     case scm_tc7_svect:
       return (   nprot
-	      || (SCM_NIMP (prot)
-		  && SCM_SYMBOLP (prot)
+	      || (SCM_SYMBOLP (prot)
 		  && (1 == SCM_LENGTH (prot))
 		  && ('s' == SCM_CHARS (prot)[0])));
 #ifdef HAVE_LONG_LONGS
     case scm_tc7_llvect:
       return (   nprot
-	      || (SCM_NIMP (prot)
-		  && SCM_SYMBOLP (prot)
+	      || (SCM_SYMBOLP (prot)
 		  && (1 == SCM_LENGTH (prot))
 		  && ('s' == SCM_CHARS (prot)[0])));
 #endif