diff --git a/http.c b/http.c
index a6d9ab3a..96c5305d 100644
--- a/http.c
+++ b/http.c
@@ -219,18 +219,25 @@ strsep(char **s, const char *del)
 }
 #endif
 
-static void 
-rtrim(char *str)
+void
+evutil_rtrim_(char *str)
 {
 	char *cp;
 
-	if( str == NULL )
+	if (str == NULL)
 		return;
 
-	cp = strchr(str, '\0') - 1;
+	if ((cp = strchr(str, '\0')) == NULL || (cp == str))
+		return;
 
-	while (cp >= str && *cp == ' ')
-		*cp-- = '\0';
+	--cp;
+
+	while (*cp == ' ') {
+		*cp = '\0';
+		if (cp == str)
+			break;
+		--cp;
+	}
 }
 
 static size_t
@@ -1927,7 +1934,7 @@ evhttp_parse_headers_(struct evhttp_request *req, struct evbuffer* buffer)
 			goto error;
 
 		svalue += strspn(svalue, " ");
-		rtrim(svalue);
+		evutil_rtrim_(svalue);
 
 		if (evhttp_add_header(headers, skey, svalue) == -1)
 			goto error;
diff --git a/test/regress_util.c b/test/regress_util.c
index 41bc8184..2f20e942 100644
--- a/test/regress_util.c
+++ b/test/regress_util.c
@@ -434,6 +434,38 @@ end:
 	;
 }
 
+static void
+test_evutil_rtrim(void *ptr)
+{
+#define TEST_TRIM(s, result) \
+	do {						\
+	    if (cp) mm_free(cp);			\
+	    cp = s ? mm_strdup(s) : NULL;		\
+	    evutil_rtrim_(cp);				\
+	    if (result == NULL)				\
+		    tt_ptr_op(cp, ==, NULL);		\
+	    else					\
+		    tt_str_op(cp, ==, result);		\
+	} while(0)
+
+	char *cp = NULL;
+	(void) ptr;
+
+	TEST_TRIM(NULL, NULL);
+	TEST_TRIM("", "");
+	TEST_TRIM("a", "a");
+	TEST_TRIM("abcdef ghi", "abcdef ghi");
+
+	TEST_TRIM(" ", "");
+	TEST_TRIM("  ", "");
+	TEST_TRIM("a ", "a");
+	TEST_TRIM("abcdef  gH       ", "abcdef  gH");
+
+end:
+	if (cp)
+		mm_free(cp);
+}
+
 static int logsev = 0;
 static char *logmsg = NULL;
 
@@ -1348,6 +1380,7 @@ struct testcase_t util_testcases[] = {
 	{ "evutil_snprintf", test_evutil_snprintf, 0, NULL, NULL },
 	{ "evutil_strtoll", test_evutil_strtoll, 0, NULL, NULL },
 	{ "evutil_casecmp", test_evutil_casecmp, 0, NULL, NULL },
+	{ "evutil_rtrim", test_evutil_rtrim, 0, NULL, NULL },
 	{ "strlcpy", test_evutil_strlcpy, 0, NULL, NULL },
 	{ "log", test_evutil_log, TT_FORK, NULL, NULL },
 	{ "upcast", test_evutil_upcast, 0, NULL, NULL },
diff --git a/util-internal.h b/util-internal.h
index da1fb838..dff3d70b 100644
--- a/util-internal.h
+++ b/util-internal.h
@@ -218,6 +218,10 @@ int EVUTIL_ISUPPER_(char c);
 char EVUTIL_TOUPPER_(char c);
 char EVUTIL_TOLOWER_(char c);
 
+/** Remove all trailing whitespace from the end of a string */
+void evutil_rtrim_(char *);
+
+
 /** Helper macro.  If we know that a given pointer points to a field in a
     structure, return a pointer to the structure itself.  Used to implement
     our half-baked C OO.  Example: