diff --git a/http_parser.c b/http_parser.c
index 9941b7ea..ba1374e9 100644
--- a/http_parser.c
+++ b/http_parser.c
@@ -314,6 +314,8 @@ enum state
   , s_req_http_HT
   , s_req_http_HTT
   , s_req_http_HTTP
+  , s_req_http_I
+  , s_req_http_IC
   , s_req_http_major
   , s_req_http_dot
   , s_req_http_minor
@@ -1084,11 +1086,17 @@ size_t http_parser_execute (http_parser *parser,
 
       case s_req_http_start:
         switch (ch) {
+          case ' ':
+            break;
           case 'H':
             UPDATE_STATE(s_req_http_H);
             break;
-          case ' ':
-            break;
+          case 'I':
+            if (parser->method == HTTP_SOURCE) {
+              UPDATE_STATE(s_req_http_I);
+              break;
+            }
+            /* fall through */
           default:
             SET_ERRNO(HPE_INVALID_CONSTANT);
             goto error;
@@ -1110,6 +1118,16 @@ size_t http_parser_execute (http_parser *parser,
         UPDATE_STATE(s_req_http_HTTP);
         break;
 
+      case s_req_http_I:
+        STRICT_CHECK(ch != 'C');
+        UPDATE_STATE(s_req_http_IC);
+        break;
+
+      case s_req_http_IC:
+        STRICT_CHECK(ch != 'E');
+        UPDATE_STATE(s_req_http_HTTP);  /* Treat "ICE" as "HTTP". */
+        break;
+
       case s_req_http_HTTP:
         STRICT_CHECK(ch != '/');
         UPDATE_STATE(s_req_http_major);
diff --git a/test.c b/test.c
index 681cc88a..115ddcac 100644
--- a/test.c
+++ b/test.c
@@ -1173,6 +1173,26 @@ const struct message requests[] =
   ,.headers= { { "Host", "example.com" } }
   ,.body= ""
   }
+
+#define SOURCE_ICE_REQUEST 42
+, {.name = "source request"
+  ,.type= HTTP_REQUEST
+  ,.raw= "SOURCE /music/sweet/music ICE/1.0\r\n"
+         "Host: example.com\r\n"
+         "\r\n"
+  ,.should_keep_alive= FALSE
+  ,.message_complete_on_eof= FALSE
+  ,.http_major= 1
+  ,.http_minor= 0
+  ,.method= HTTP_SOURCE
+  ,.request_path= "/music/sweet/music"
+  ,.request_url= "/music/sweet/music"
+  ,.query_string= ""
+  ,.fragment= ""
+  ,.num_headers= 1
+  ,.headers= { { "Host", "example.com" } }
+  ,.body= ""
+  }
 };
 
 /* * R E S P O N S E S * */
@@ -4268,6 +4288,8 @@ main (void)
 
   /// REQUESTS
 
+  test_simple("GET / IHTTP/1.0\r\n\r\n", HPE_INVALID_CONSTANT);
+  test_simple("GET / ICE/1.0\r\n\r\n", HPE_INVALID_CONSTANT);
   test_simple("GET / HTP/1.1\r\n\r\n", HPE_INVALID_VERSION);
   test_simple("GET / HTTP/01.1\r\n\r\n", HPE_INVALID_VERSION);
   test_simple("GET / HTTP/11.1\r\n\r\n", HPE_INVALID_VERSION);