--- a/rpmdb/rpmvercmp.c	
+++ a/rpmdb/rpmvercmp.c	
@@ -34,8 +34,10 @@ int rpmvercmp(const char * a, const char * b)
 
     /* loop through each version segment of str1 and str2 and compare them */
     while (*one && *two) {
-	while (*one && !xisalnum(*one)) one++;
-	while (*two && !xisalnum(*two)) two++;
+	if ((*one && !xisalnum(*one)) && (*two && !xisalnum(*two))) {
+	    while (*one && !xisalnum(*one)) one++;
+	    while (*two && !xisalnum(*two)) two++;
+	}
 
 	if ( !*one && !*two )
 		return 0;