diff --git a/dlls/wininet/internet.c b/dlls/wininet/internet.c
index 5beb6223efe..5930ea5a8f0 100644
--- a/dlls/wininet/internet.c
+++ b/dlls/wininet/internet.c
@@ -3781,7 +3781,11 @@ static BOOL calc_url_length(LPURL_COMPONENTSW lpUrlComponents,
     }
 
     if (lpUrlComponents->lpszHostName)
+    {
         *lpdwUrlLength += URL_GET_COMP_LENGTH(lpUrlComponents, HostName);
+        if (lpUrlComponents->lpszUrlPath && *lpUrlComponents->lpszUrlPath != '/')
+            (*lpdwUrlLength)++; /* '/' */
+    }
 
     if (!url_uses_default_port(nScheme, lpUrlComponents->nPort))
     {
@@ -4011,6 +4015,13 @@ BOOL WINAPI InternetCreateUrlW(LPURL_COMPONENTSW lpUrlComponents, DWORD dwFlags,
         dwLen = URL_GET_COMP_LENGTH(lpUrlComponents, HostName);
         memcpy(lpszUrl, lpUrlComponents->lpszHostName, dwLen * sizeof(WCHAR));
         lpszUrl += dwLen;
+
+        /* add slash between hostname and path if necessary */
+        if (lpUrlComponents->lpszUrlPath && *lpUrlComponents->lpszUrlPath != '/')
+        {
+            *lpszUrl = '/';
+            lpszUrl++;
+        }
     }
 
     if (!url_uses_default_port(nScheme, lpUrlComponents->nPort))
diff --git a/dlls/wininet/tests/http.c b/dlls/wininet/tests/http.c
index 90a972c2d94..a4b66ebec72 100644
--- a/dlls/wininet/tests/http.c
+++ b/dlls/wininet/tests/http.c
@@ -48,6 +48,7 @@
 #define CREATE_URL7 "http://username:password@www.winehq.org:42/site/about"
 #define CREATE_URL8 "https://username:password@www.winehq.org/site/about"
 #define CREATE_URL9 "about:blank"
+#define CREATE_URL10 "about://host/blank"
 
 static HANDLE hCompleteEvent;
 
@@ -1109,6 +1110,7 @@ static void InternetCreateUrlA_test(void)
 	urlComp.lpszUrlPath = "blank";
 	urlComp.dwUrlPathLength = 5;
 	len = strlen(CREATE_URL9);
+	len++; /* work around bug in native wininet */
 	szUrl = (char *)HeapAlloc(GetProcessHeap(), 0, ++len);
 	ret = InternetCreateUrlA(&urlComp, ICU_ESCAPE, szUrl, &len);
 	ok(ret, "Expected success\n");
@@ -1116,6 +1118,21 @@ static void InternetCreateUrlA_test(void)
 	ok(!strcmp(szUrl, CREATE_URL9), "Expected %s, got %s\n", CREATE_URL9, szUrl);
 
 	HeapFree(GetProcessHeap(), 0, szUrl);
+
+	memset(&urlComp, 0, sizeof(urlComp));
+	urlComp.dwStructSize = sizeof(URL_COMPONENTS);
+	urlComp.lpszScheme = "about";
+	urlComp.lpszHostName = "host";
+	urlComp.lpszUrlPath = "blank";
+	len = strlen(CREATE_URL10);
+	len++; /* work around bug in native wininet */
+	szUrl = (char *)HeapAlloc(GetProcessHeap(), 0, ++len);
+	ret = InternetCreateUrlA(&urlComp, ICU_ESCAPE, szUrl, &len);
+	ok(ret, "Expected success\n");
+	ok(len == strlen(CREATE_URL10), "Expected len %d, got %ld\n", strlen(CREATE_URL9), len);
+	ok(!strcmp(szUrl, CREATE_URL10), "Expected %s, got %s\n", CREATE_URL9, szUrl);
+
+	HeapFree(GetProcessHeap(), 0, szUrl);
 }
 
 static void HttpSendRequestEx_test(void)