diff --git a/convert.c b/convert.c
index 308fa3f..a6a41ba 100644
--- a/convert.c
+++ b/convert.c
@@ -250,6 +250,8 @@
 	CHECK_PARAM_NOT_NULL(w);
 	while (w) {
 	 	char *s = word_string (w);
+                if (!s)
+                        return;
 		if (*s == '\\') {
 			++s;
 			if (!strncmp (s, "yr", 2) && isdigit(s[2])) {
@@ -333,6 +335,8 @@
 
 		if ((w2=w->child)) {
 			tmp = word_string (w2);
+			if(!tmp)
+				break;
 			if (!strncmp("\\f",tmp,2)) {
 				num = atoi (&tmp[2]);
 				name[0]=0;
@@ -461,14 +465,15 @@
 			char *s;
 
 			s = word_string(child);
-
+                        if (!s)
+                                return;
 			if (!inline_mode) {
 				if (!strcmp("\\title", s)) {
 					printf (op->document_title_begin);
 					w2=child->next;
 					while (w2) {
 						char *s2 = word_string(w2);
-						if (s2[0] != '\\') 
+						if (s2 && s2[0] != '\\') 
 							printf ("%s", s2);
 						w2=w2->next;
 					}
@@ -479,7 +484,7 @@
 					w2=child->next;
 					while (w2) {
 						char *s2 = word_string(w2);
-						if (s2[0] != '\\') 
+						if (s2 && s2[0] != '\\') 
 							printf ("%s,", s2);
 						w2=w2->next;
 					}
@@ -490,7 +495,7 @@
 					w2=child->next;
 					while (w2) {
 						char *s2 = word_string(w2);
-						if (s2[0] != '\\') 
+						if (s2 && s2[0] != '\\') 
 							printf ("%s", s2);
 						w2=w2->next;
 					}
@@ -502,7 +507,7 @@
 					w2=child->next;
 					while (w2) {
 						char *s2 = word_string(w2);
-						if (s2[0] != '\\') 
+						if (s2 && s2[0] != '\\') 
 							printf ("%s", s2);
 						w2=w2->next;
 					}
@@ -612,10 +617,10 @@
 	r=g=b=0;
 
 	while(w) {
-                if (total_colors >= MAX_COLORS) {
+		char *s = word_string (w);
+                if (s == 0 || total_colors >= MAX_COLORS) {
                         break;
                 }
-		char *s = word_string (w);
 
 #if 0
 		printf (op->comment_begin);
@@ -777,7 +782,7 @@
 						if(s && !strcmp(s, "SYMBOL") )
 						{
 						w4=w3->next;
-						while(w4 && !strcmp(word_string(w4), " "))
+						while(w4 && word_string(w4) && !strcmp(word_string(w4), " "))
 							w4 = w4->next;
 						s4 = word_string(w4);
 						if(s4)
@@ -795,7 +800,7 @@
 								Word *w4;
 								char *s4;
 								w4=w3->next;
-								while (w4 && !strcmp(" ", word_string(w4)))
+								while (w4 && word_string(w4) && !strcmp(" ", word_string(w4)))
 									w4=w4->next;
 								if (w4) {
 									s4=word_string(w4);