diff --git a/src/detect-engine.c b/src/detect-engine.c
index da8a4a8234..5b82b68b00 100644
--- a/src/detect-engine.c
+++ b/src/detect-engine.c
@@ -47,7 +47,6 @@
 #include "detect-engine-uri.h"
 #include "detect-engine-hrhd.h"
 #include "detect-engine-file.h"
-#include "detect-engine-modbus.h"
 #include "detect-engine-template.h"
 
 #include "detect-engine.h"
@@ -123,10 +122,6 @@ void DetectEngineRegisterAppInspectionEngines(void)
         { ALPROTO_SMTP,
           DETECT_SM_LIST_FILEMATCH,
           DetectFileInspectSmtp },
-        /* Modbus */
-        { ALPROTO_MODBUS,
-          DETECT_SM_LIST_MODBUS_MATCH,
-          DetectEngineInspectModbus },
         /* Template. */
         { ALPROTO_TEMPLATE,
           DETECT_SM_LIST_TEMPLATE_BUFFER_MATCH,
@@ -137,10 +132,6 @@ void DetectEngineRegisterAppInspectionEngines(void)
         { ALPROTO_HTTP,
           DETECT_SM_LIST_FILEMATCH,
           DetectFileInspectHttp },
-        /* Modbus */
-        { ALPROTO_MODBUS,
-          DETECT_SM_LIST_MODBUS_MATCH,
-          DetectEngineInspectModbus },
         /* Template. */
         { ALPROTO_TEMPLATE,
           DETECT_SM_LIST_TEMPLATE_BUFFER_MATCH,
diff --git a/src/detect-modbus.c b/src/detect-modbus.c
index fe585f6d12..b426b4b2c8 100644
--- a/src/detect-modbus.c
+++ b/src/detect-modbus.c
@@ -45,8 +45,10 @@
 
 #include "detect.h"
 #include "detect-parse.h"
+#include "detect-engine.h"
 
 #include "detect-modbus.h"
+#include "detect-engine-modbus.h"
 
 #include "util-debug.h"
 
@@ -412,11 +414,16 @@ void DetectModbusRegister(void)
             &function_parse_regex, &function_parse_regex_study);
     DetectSetupParseRegexes(PARSE_REGEX_ACCESS,
             &access_parse_regex, &access_parse_regex_study);
+
+    DetectAppLayerInspectEngineRegister(ALPROTO_MODBUS, SIG_FLAG_TOSERVER,
+            DETECT_SM_LIST_MODBUS_MATCH,
+            DetectEngineInspectModbus);
+    DetectAppLayerInspectEngineRegister(ALPROTO_MODBUS, SIG_FLAG_TOCLIENT,
+            DETECT_SM_LIST_MODBUS_MATCH,
+            DetectEngineInspectModbus);
 }
 
 #ifdef UNITTESTS /* UNITTESTS */
-#include "detect-engine.h"
-
 #include "util-unittest.h"
 
 /** \test Signature containing a function. */