diff --git a/configure.ac b/configure.ac
index 95775e80a757..14110bf212c4 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1560,6 +1560,7 @@
         AC_CHECK_LIB([htp], [htp_tx_get_response_headers_raw],AC_DEFINE_UNQUOTED([HAVE_HTP_TX_GET_RESPONSE_HEADERS_RAW],[1],[Found htp_tx_get_response_headers_raw in libhtp]) ,,[-lhtp])
         AC_CHECK_LIB([htp], [htp_decode_query_inplace],AC_DEFINE_UNQUOTED([HAVE_HTP_DECODE_QUERY_INPLACE],[1],[Found htp_decode_query_inplace function in libhtp]) ,,[-lhtp])
         AC_CHECK_LIB([htp], [htp_config_set_response_decompression_layer_limit],AC_DEFINE_UNQUOTED([HAVE_HTP_CONFIG_SET_RESPONSE_DECOMPRESSION_LAYER_LIMIT],[1],[Found htp_config_set_response_decompression_layer_limit function in libhtp]) ,,[-lhtp])
+        AC_CHECK_LIB([htp], [htp_config_set_allow_space_uri],AC_DEFINE_UNQUOTED([HAVE_HTP_CONFIG_SET_ALLOW_SPACE_URI],[1],[Found htp_config_set_allow_space_uri function in libhtp]) ,,[-lhtp])
         AC_EGREP_HEADER(htp_config_set_path_decode_u_encoding, htp/htp.h, AC_DEFINE_UNQUOTED([HAVE_HTP_SET_PATH_DECODE_U_ENCODING],[1],[Found usable htp_config_set_path_decode_u_encoding function in libhtp]) )
         AC_CHECK_LIB([htp], [htp_config_set_lzma_memlimit],AC_DEFINE_UNQUOTED([HAVE_HTP_CONFIG_SET_LZMA_MEMLIMIT],[1],[Found htp_config_set_lzma_memlimit function in libhtp]) ,,[-lhtp])
         AC_CHECK_LIB([htp], [htp_config_set_lzma_layers],AC_DEFINE_UNQUOTED([HAVE_HTP_CONFIG_SET_LZMA_LAYERS],[1],[Found htp_config_set_lzma_layers function in libhtp]) ,,[-lhtp])
@@ -1585,6 +1586,7 @@
             AC_DEFINE_UNQUOTED([HAVE_HTP_DECODE_QUERY_INPLACE],[1],[Assuming htp_decode_query_inplace function in bundled libhtp])
             # enable when libhtp has been updated
             AC_DEFINE_UNQUOTED([HAVE_HTP_CONFIG_SET_RESPONSE_DECOMPRESSION_LAYER_LIMIT],[1],[Assuming htp_config_set_response_decompression_layer_limit function in bundled libhtp])
+            AC_DEFINE_UNQUOTED([HAVE_HTP_CONFIG_SET_ALLOW_SPACE_URI],[1],[Assuming htp_config_set_allow_space_uri function in bundled libhtp])
             AC_DEFINE_UNQUOTED([HAVE_HTP_CONFIG_SET_LZMA_MEMLIMIT],[1],[Assuming htp_config_set_lzma_memlimit function in bundled libhtp])
             AC_DEFINE_UNQUOTED([HAVE_HTP_CONFIG_SET_LZMA_LAYERS],[1],[Assuming htp_config_set_lzma_layers function in bundled libhtp])
             AC_DEFINE_UNQUOTED([HAVE_HTP_CONFIG_SET_COMPRESSION_BOMB_LIMIT],[1],[Assuming htp_config_set_compression_bomb_limit function in bundled libhtp])
diff --git a/doc/userguide/upgrade.rst b/doc/userguide/upgrade.rst
index 473c8cd488aa..df949a76694a 100644
--- a/doc/userguide/upgrade.rst
+++ b/doc/userguide/upgrade.rst
@@ -41,6 +41,9 @@ Major changes
   change for the default behavior in the Exception Policies: in IPS mode, if an
   exception policy is not set, it will fall back to the the master switch now,
   instead of being ignored. Prevent this by disabling the master switch.
+- Spaces are accepted in HTTP1 URIs instead of in the protocol version. That is:
+  `GET /a b HTTP/1.1` gets now URI as `/a b` and protocol as `HTTP/1.1` when
+  it used to be URI as `/a` and protocol as `b HTTP/1.1`
 
 Security changes
 ~~~~~~~~~~~~~~~~
diff --git a/src/app-layer-htp.c b/src/app-layer-htp.c
index ee4295cf72e3..1bc5eb33e141 100644
--- a/src/app-layer-htp.c
+++ b/src/app-layer-htp.c
@@ -2469,6 +2469,9 @@ static void HTPConfigSetDefaultsPhase1(HTPCfgRec *cfg_prec)
     htp_config_register_response_complete(cfg_prec->cfg, HTPCallbackResponseComplete);
 
     htp_config_set_parse_request_cookies(cfg_prec->cfg, 0);
+#ifdef HAVE_HTP_CONFIG_SET_ALLOW_SPACE_URI
+    htp_config_set_allow_space_uri(cfg_prec->cfg, 1);
+#endif
 
     /* don't convert + to space by default */
     htp_config_set_plusspace_decode(cfg_prec->cfg, HTP_DECODER_URLENCODED, 0);
diff --git a/src/detect-http-protocol.c b/src/detect-http-protocol.c
index 162066ebeea6..588381a8282e 100644
--- a/src/detect-http-protocol.c
+++ b/src/detect-http-protocol.c
@@ -114,6 +114,26 @@ static InspectionBuffer *GetData(DetectEngineThreadCtx *det_ctx,
     return buffer;
 }
 
+static bool DetectHttpProtocolValidateCallback(const Signature *s, const char **sigerror)
+{
+#ifdef HAVE_HTP_CONFIG_SET_ALLOW_SPACE_URI
+    const SigMatch *sm = s->init_data->smlists[g_buffer_id];
+    for (; sm != NULL; sm = sm->next) {
+        if (sm->type != DETECT_CONTENT)
+            continue;
+        const DetectContentData *cd = (DetectContentData *)sm->ctx;
+        for (size_t i = 0; i < cd->content_len; ++i) {
+            if (cd->content[i] == ' ') {
+                *sigerror = "Invalid http.protocol string containing a space";
+                SCLogWarning("rule %u: %s", s->id, *sigerror);
+                return false;
+            }
+        }
+    }
+#endif
+    return true;
+}
+
 /**
  * \brief Registers the keyword handlers for the "http.protocol" keyword.
  */
@@ -137,6 +157,7 @@ void DetectHttpProtocolRegister(void)
 
     DetectBufferTypeSetDescriptionByName(BUFFER_NAME,
             BUFFER_DESC);
+    DetectBufferTypeRegisterValidateCallback(BUFFER_NAME, DetectHttpProtocolValidateCallback);
 
     g_buffer_id = DetectBufferTypeGetByName(BUFFER_NAME);
 }