diff --git a/common/controls.c b/common/controls.c
index 483fec4f..096bc6b2 100644
--- a/common/controls.c
+++ b/common/controls.c
@@ -1,5 +1,6 @@
 // 8 june 2019
 #include "uipriv.h"
+#include "testhooks.h"
 
 struct controlType {
 	uint32_t id;
@@ -202,3 +203,13 @@ void *uiControlImplData(uiControl *c)
 	}
 	return c->implData;
 }
+
+static uiControl testHookControlWithInvalidType = {
+	.controlID = controlTypeID,
+	.typeID = 5,
+};
+
+uiControl *uiprivTestHookControlWithInvalidType(void)
+{
+	return &testHookControlWithInvalidType;
+}
diff --git a/common/testhooks.h b/common/testhooks.h
index 986c6fc4..a6076001 100644
--- a/common/testhooks.h
+++ b/common/testhooks.h
@@ -8,6 +8,9 @@ extern "C" {
 typedef void (*uiprivTestHookReportProgrammerErrorFunc)(const char *msg, void *data);
 uiprivExtern void uiprivTestHookReportProgrammerError(uiprivTestHookReportProgrammerErrorFunc f, void *data);
 
+// controls.c
+uiprivExtern uiControl *uiprivTestHookControlWithInvalidType(void);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/test/controls_errors.cpp b/test/controls_errors.cpp
index f581e32f..783f2cc5 100644
--- a/test/controls_errors.cpp
+++ b/test/controls_errors.cpp
@@ -73,9 +73,16 @@ static const struct checkErrorCase casesAfterOSVtable[] = {
 	{
 		"uiCheckControlType() with a control with an unknown type",
 		[](void) {
-			// TODO
+			uiCheckControlType(uiprivTestHookControlWithInvalidType(), testControlType);
 		},
-		"TODO",
+		"uiCheckControlType(): unknown uiControl type 5 found in uiControl (this is likely not a real uiControl or some data is corrupt)",
+	},
+	{
+		"uiCheckControlType() with a control with an unknown type, even with uiControlType()",
+		[](void) {
+			uiCheckControlType(uiprivTestHookControlWithInvalidType(), uiControlType());
+		},
+		"uiCheckControlType(): unknown uiControl type 5 found in uiControl (this is likely not a real uiControl or some data is corrupt)",
 	},
 	{
 		"uiCheckControlType() asking for an unknown control type",