diff --git a/libsrc/attr.m4 b/libsrc/attr.m4
index 94bebf2386..dba0238e18 100644
--- a/libsrc/attr.m4
+++ b/libsrc/attr.m4
@@ -230,15 +230,18 @@ dup_NC_attrarrayV(NC_attrarray *ncap, const NC_attrarray *ref)
 	ncap->nelems = 0;
 	{
 		NC_attr **app = ncap->value;
-		const NC_attr **drpp = (const NC_attr **)ref->value;
-		NC_attr *const *const end = &app[ref->nelems];
-		for( /*NADA*/; app < end; drpp++, app++, ncap->nelems++)
+		if (app)
 		{
-			*app = dup_NC_attr(*drpp);
-			if(*app == NULL)
+			const NC_attr **drpp = (const NC_attr **)ref->value;
+			NC_attr *const *const end = &app[ref->nelems];
+			for( /*NADA*/; app < end; drpp++, app++, ncap->nelems++)
 			{
-				status = NC_ENOMEM;
-				break;
+				*app = dup_NC_attr(*drpp);
+				if(*app == NULL)
+				{
+					status = NC_ENOMEM;
+					break;
+				}
 			}
 		}
 	}
diff --git a/libsrc/dim.c b/libsrc/dim.c
index 227ac5ab5c..dea0fac3dc 100644
--- a/libsrc/dim.c
+++ b/libsrc/dim.c
@@ -228,15 +228,18 @@ dup_NC_dimarrayV(NC_dimarray *ncap, const NC_dimarray *ref)
 	ncap->nelems = 0;
 	{
 		NC_dim **dpp = ncap->value;
-		const NC_dim **drpp = (const NC_dim **)ref->value;
-		NC_dim *const *const end = &dpp[ref->nelems];
-		for( /*NADA*/; dpp < end; drpp++, dpp++, ncap->nelems++)
+		if(dpp != NULL)
 		{
-			*dpp = dup_NC_dim(*drpp);
-			if(*dpp == NULL)
+			const NC_dim **drpp = (const NC_dim **)ref->value;
+			NC_dim *const *const end = &dpp[ref->nelems];
+			for( /*NADA*/; dpp < end; drpp++, dpp++, ncap->nelems++)
 			{
-				status = NC_ENOMEM;
-				break;
+				*dpp = dup_NC_dim(*drpp);
+				if(*dpp == NULL)
+				{
+					status = NC_ENOMEM;
+					break;
+				}
 			}
 		}
 	}
diff --git a/libsrc/nc3internal.c b/libsrc/nc3internal.c
index 2045304e05..0916cc9500 100644
--- a/libsrc/nc3internal.c
+++ b/libsrc/nc3internal.c
@@ -950,7 +950,6 @@ int
 NC_calcsize(const NC3_INFO *ncp, off_t *calcsizep)
 {
 	NC_var **vpp = (NC_var **)ncp->vars.value;
-	NC_var *const *const end = &vpp[ncp->vars.nelems];
 	NC_var *last_fix = NULL;	/* last "non-record" var */
 	int numrecvars = 0;	/* number of record variables */
 
@@ -960,12 +959,16 @@ NC_calcsize(const NC3_INFO *ncp, off_t *calcsizep)
 	    return NC_NOERR;
 	}
 
-	for( /*NADA*/; vpp < end; vpp++) {
-	    if(IS_RECVAR(*vpp)) {
-		numrecvars++;
-	    } else {
-		last_fix = *vpp;
-	    }
+	if (vpp)
+	{
+		NC_var *const *const end = &vpp[ncp->vars.nelems];
+		for( /*NADA*/; vpp < end; vpp++) {
+		    if(IS_RECVAR(*vpp)) {
+			numrecvars++;
+		    } else {
+			last_fix = *vpp;
+		    }
+		}
 	}
 
 	if(numrecvars == 0) {
diff --git a/libsrc/putget.m4 b/libsrc/putget.m4
index 2779480bab..9a0aca8a27 100644
--- a/libsrc/putget.m4
+++ b/libsrc/putget.m4
@@ -551,7 +551,7 @@ static int
 NCedgeck(const NC3_INFO* ncp, const NC_var *varp,
 	 const size_t *start, const size_t *edges)
 {
-	const size_t *const end = start + varp->ndims;
+	const size_t *const end = start ? (start + varp->ndims) : NULL;
 	const size_t *shp = varp->shape;
 
 	if(varp->ndims == 0)
diff --git a/libsrc/v1hpg.c b/libsrc/v1hpg.c
index 63172f2274..f93b219bdb 100644
--- a/libsrc/v1hpg.c
+++ b/libsrc/v1hpg.c
@@ -448,10 +448,13 @@ ncx_len_NC_dimarray(const NC_dimarray *ncap, int version)
 	/* else */
 	{
 		const NC_dim **dpp = (const NC_dim **)ncap->value;
-		const NC_dim *const *const end = &dpp[ncap->nelems];
-		for(  /*NADA*/; dpp < end; dpp++)
+		if (dpp)
 		{
-			xlen += ncx_len_NC_dim(*dpp,version);
+			const NC_dim *const *const end = &dpp[ncap->nelems];
+			for(  /*NADA*/; dpp < end; dpp++)
+			{
+				xlen += ncx_len_NC_dim(*dpp,version);
+			}
 		}
 	}
 	return xlen;
@@ -641,11 +644,13 @@ v1h_put_NC_attrV(v1hs *psp, const NC_attr *attrp)
 		if(status != NC_NOERR)
 			return status;
 
-		(void) memcpy(psp->pos, value, nbytes);
-
+		if (value) {
+			(void) memcpy(psp->pos, value, nbytes);
+			value = (void *)((char *)value + nbytes);
+		}
+		
 		psp->pos = (void *)((char *)psp->pos + nbytes);
-		value = (void *)((char *)value + nbytes);
-        	remaining -= nbytes;
+		remaining -= nbytes;
 
 	} while(remaining != 0);
 
@@ -709,11 +714,13 @@ v1h_get_NC_attrV(v1hs *gsp, NC_attr *attrp)
 		if(status != NC_NOERR)
 			return status;
 
-		(void) memcpy(value, gsp->pos, nget);
+		if (value) {
+			(void) memcpy(value, gsp->pos, nget);
+			value = (void *)((signed char *)value + nget);
+		}
+		
 		gsp->pos = (void*)((unsigned char *)gsp->pos + nget);
 
-		value = (void *)((signed char *)value + nget);
-
 		remaining -= nget;
 
 	} while(remaining != 0);
@@ -790,10 +797,13 @@ ncx_len_NC_attrarray(const NC_attrarray *ncap, int version)
 	/* else */
 	{
 		const NC_attr **app = (const NC_attr **)ncap->value;
-		const NC_attr *const *const end = &app[ncap->nelems];
-		for( /*NADA*/; app < end; app++)
+		if (app)
 		{
-			xlen += ncx_len_NC_attr(*app,version);
+			const NC_attr *const *const end = &app[ncap->nelems];
+			for( /*NADA*/; app < end; app++)
+			{
+				xlen += ncx_len_NC_attr(*app,version);
+			}
 		}
 	}
 	return xlen;
@@ -1090,10 +1100,13 @@ ncx_len_NC_vararray(const NC_vararray *ncap, size_t sizeof_off_t, int version)
 	/* else */
 	{
 		const NC_var **vpp = (const NC_var **)ncap->value;
-		const NC_var *const *const end = &vpp[ncap->nelems];
-		for( /*NADA*/; vpp < end; vpp++)
+		if (vpp)
 		{
-			xlen += ncx_len_NC_var(*vpp, sizeof_off_t, version);
+			const NC_var *const *const end = &vpp[ncap->nelems];
+			for( /*NADA*/; vpp < end; vpp++)
+			{
+				xlen += ncx_len_NC_var(*vpp, sizeof_off_t, version);
+			}
 		}
 	}
 	return xlen;
@@ -1224,7 +1237,6 @@ static int
 NC_computeshapes(NC3_INFO* ncp)
 {
 	NC_var **vpp = (NC_var **)ncp->vars.value;
-	NC_var *const *const end = &vpp[ncp->vars.nelems];
 	NC_var *first_var = NULL;	/* first "non-record" var */
 	NC_var *first_rec = NULL;	/* first "record" var */
 	int status;
@@ -1236,27 +1248,31 @@ NC_computeshapes(NC3_INFO* ncp)
 	if(ncp->vars.nelems == 0)
 		return(0);
 
-	for( /*NADA*/; vpp < end; vpp++)
+	if (vpp)
 	{
-		status = NC_var_shape(*vpp, &ncp->dims);
-        if(status != NC_NOERR)
-			return(status);
-
-	  	if(IS_RECVAR(*vpp))
-		{
-	  		if(first_rec == NULL)
-				first_rec = *vpp;
-			    ncp->recsize += (*vpp)->len;
-		}
-		else
+		NC_var *const *const end = &vpp[ncp->vars.nelems];
+		for( /*NADA*/; vpp < end; vpp++)
 		{
+			status = NC_var_shape(*vpp, &ncp->dims);
+	        if(status != NC_NOERR)
+				return(status);
+
+		  	if(IS_RECVAR(*vpp))
+			{
+		  		if(first_rec == NULL)
+					first_rec = *vpp;
+				ncp->recsize += (*vpp)->len;
+			}
+			else
+			{
 		        if(first_var == NULL)
 			        first_var = *vpp;
-			/*
-			 * Overwritten each time thru.
-			 * Usually overwritten in first_rec != NULL clause below.
-			 */
-			ncp->begin_rec = (*vpp)->begin + (off_t)(*vpp)->len;
+				/*
+				 * Overwritten each time thru.
+				 * Usually overwritten in first_rec != NULL clause below.
+				 */
+				ncp->begin_rec = (*vpp)->begin + (off_t)(*vpp)->len;
+			}
 		}
 	}
 
diff --git a/libsrc/var.c b/libsrc/var.c
index f09bbe27bd..c8cd64dcd6 100644
--- a/libsrc/var.c
+++ b/libsrc/var.c
@@ -267,14 +267,17 @@ dup_NC_vararrayV(NC_vararray *ncap, const NC_vararray *ref)
 	{
 		NC_var **vpp = ncap->value;
 		const NC_var **drpp = (const NC_var **)ref->value;
-		NC_var *const *const end = &vpp[ref->nelems];
-		for( /*NADA*/; vpp < end; drpp++, vpp++, ncap->nelems++)
+		if (vpp)
 		{
-			*vpp = dup_NC_var(*drpp);
-			if(*vpp == NULL)
+			NC_var *const *const end = &vpp[ref->nelems];
+			for( /*NADA*/; vpp < end; drpp++, vpp++, ncap->nelems++)
 			{
-				status = NC_ENOMEM;
-				break;
+				*vpp = dup_NC_var(*drpp);
+				if(*vpp == NULL)
+				{
+					status = NC_ENOMEM;
+					break;
+				}
 			}
 		}
 	}