diff --git a/app/src/main/res/layout/cpp_unit_converter.xml b/app/src/main/res/layout/cpp_unit_converter.xml
index 9877258a..d3e50cf5 100644
--- a/app/src/main/res/layout/cpp_unit_converter.xml
+++ b/app/src/main/res/layout/cpp_unit_converter.xml
@@ -71,7 +71,7 @@
                         android:id="@+id/converter_edittext_from"
                         android:layout_width="match_parent"
                         android:layout_height="match_parent"
-                        android:inputType="numberDecimal"
+                        android:inputType="numberDecimal|numberSigned"
                         android:singleLine="true" />
                 </android.support.design.widget.TextInputLayout>
 
diff --git a/app/src/main/res/layout/fragment_variable_edit.xml b/app/src/main/res/layout/fragment_variable_edit.xml
index 7189a88e..7c39891e 100644
--- a/app/src/main/res/layout/fragment_variable_edit.xml
+++ b/app/src/main/res/layout/fragment_variable_edit.xml
@@ -75,7 +75,7 @@
                 a:layout_width="match_parent"
                 a:layout_height="wrap_content"
                 a:hint="@string/c_var_value"
-                a:inputType="numberDecimal" />
+                a:inputType="numberDecimal|numberSigned" />
         </android.support.design.widget.TextInputLayout>
 
         <android.support.design.widget.TextInputLayout