diff --git a/src/libavrdude.h b/src/libavrdude.h
index dc10882d..67fe00e9 100644
--- a/src/libavrdude.h
+++ b/src/libavrdude.h
@@ -1678,6 +1678,7 @@ extern "C" {
   int str_casematched_by(const char *string, const char *pattern);
   int str_is_pattern(const char *str);
   int str_is_in_list(const char *s, const char **l, size_t nl, int (*f)(const char *, const char *));
+  int str_busdev_eq(const char *s, const char *t);
   char *str_sprintf(const char *fmt, ...)
 #if defined(__GNUC__)           // Ask gcc to check whether format and parameters match
     __attribute__((format(printf, 1, 2)))
diff --git a/src/strutil.c b/src/strutil.c
index d58f0c28..fcb12232 100644
--- a/src/strutil.c
+++ b/src/strutil.c
@@ -241,6 +241,23 @@ int str_is_in_list(const char *s, const char **l, size_t nl, int (*f)(const char
   return 0;
 }
 
+// Do the two strings represent the same decimal number or are they the same up to a limiting colon?
+int str_busdev_eq(const char *s, const char *t) {
+  if(*s >= '0' && *s <='9' && *t >= '0' && *t <='9') // Both look like a decimal number
+    if(strtoull(s, NULL, 10) == strtoull(t, NULL, 10))
+      return 1;
+
+  int len = 0;                  // Length of strings up to optional colon
+  while(s[len] && s[len] != ':' && t[len] && t[len] != ':')
+    len++;
+
+  // Different length means strings are not the same
+  if((s[len] && s[len] != ':') || (t[len] && t[len] != ':'))
+    return 0;
+
+  return !strncmp(s, t, len);
+}
+
 // Return a mmt_malloc'd string with the sprintf() result
 char *str_sprintf(const char *fmt, ...) {
   int size = 0;