diff --git a/include/internal/catch_console_colour_impl.hpp b/include/internal/catch_console_colour_impl.hpp
index ba2a9d1c..426bba29 100644
--- a/include/internal/catch_console_colour_impl.hpp
+++ b/include/internal/catch_console_colour_impl.hpp
@@ -9,6 +9,7 @@
 #define TWOBLUECUBES_CATCH_CONSOLE_COLOUR_IMPL_HPP_INCLUDED
 
 #include "catch_console_colour.hpp"
+#include "catch_errno_guard.hpp"
 
 namespace Catch {
     namespace {
@@ -148,6 +149,7 @@ namespace {
     };
 
     IColourImpl* platformColourInstance() {
+        ErrnoGuard guard;
         Ptr<IConfig const> config = getCurrentContext().getConfig();
         UseColour::YesOrNo colourMode = config
             ? config->useColour()
diff --git a/projects/SelfTest/Baselines/console.std.approved.txt b/projects/SelfTest/Baselines/console.std.approved.txt
index e5dd3d31..fe0c0863 100644
--- a/projects/SelfTest/Baselines/console.std.approved.txt
+++ b/projects/SelfTest/Baselines/console.std.approved.txt
@@ -3,6 +3,17 @@
 <exe-name> is a <version> host application.
 Run with -? for options
 
+-------------------------------------------------------------------------------
+#835 -- errno should not be touched by Catch
+-------------------------------------------------------------------------------
+MiscTests.cpp:<line number>
+...............................................................................
+
+MiscTests.cpp:<line number>: FAILED:
+  CHECK( f() == 0 )
+with expansion:
+  1 == 0
+
 -------------------------------------------------------------------------------
 'Not' checks that should fail
 -------------------------------------------------------------------------------
@@ -890,6 +901,6 @@ with expansion:
   "first" == "second"
 
 ===============================================================================
-test cases: 164 | 119 passed | 43 failed |  2 failed as expected
-assertions: 955 | 851 passed | 86 failed | 18 failed as expected
+test cases: 165 | 119 passed | 44 failed |  2 failed as expected
+assertions: 957 | 852 passed | 87 failed | 18 failed as expected
 
diff --git a/projects/SelfTest/Baselines/console.sw.approved.txt b/projects/SelfTest/Baselines/console.sw.approved.txt
index 72d5dc07..4c92d229 100644
--- a/projects/SelfTest/Baselines/console.sw.approved.txt
+++ b/projects/SelfTest/Baselines/console.sw.approved.txt
@@ -48,6 +48,23 @@ PASSED:
 with expansion:
   42 == {?}
 
+-------------------------------------------------------------------------------
+#835 -- errno should not be touched by Catch
+-------------------------------------------------------------------------------
+MiscTests.cpp:<line number>
+...............................................................................
+
+MiscTests.cpp:<line number>: FAILED:
+  CHECK( f() == 0 )
+with expansion:
+  1 == 0
+
+MiscTests.cpp:<line number>:
+PASSED:
+  REQUIRE( (*__errno_location ()) == 1 )
+with expansion:
+  1 == 1
+
 -------------------------------------------------------------------------------
 'Not' checks that should fail
 -------------------------------------------------------------------------------
@@ -9350,6 +9367,6 @@ MiscTests.cpp:<line number>:
 PASSED:
 
 ===============================================================================
-test cases: 164 | 118 passed | 44 failed |  2 failed as expected
-assertions: 957 | 851 passed | 88 failed | 18 failed as expected
+test cases: 165 | 118 passed | 45 failed |  2 failed as expected
+assertions: 959 | 852 passed | 89 failed | 18 failed as expected
 
diff --git a/projects/SelfTest/Baselines/console.swa4.approved.txt b/projects/SelfTest/Baselines/console.swa4.approved.txt
index 098c33d2..6c4f19a0 100644
--- a/projects/SelfTest/Baselines/console.swa4.approved.txt
+++ b/projects/SelfTest/Baselines/console.swa4.approved.txt
@@ -48,6 +48,23 @@ PASSED:
 with expansion:
   42 == {?}
 
+-------------------------------------------------------------------------------
+#835 -- errno should not be touched by Catch
+-------------------------------------------------------------------------------
+MiscTests.cpp:<line number>
+...............................................................................
+
+MiscTests.cpp:<line number>: FAILED:
+  CHECK( f() == 0 )
+with expansion:
+  1 == 0
+
+MiscTests.cpp:<line number>:
+PASSED:
+  REQUIRE( (*__errno_location ()) == 1 )
+with expansion:
+  1 == 1
+
 -------------------------------------------------------------------------------
 'Not' checks that should fail
 -------------------------------------------------------------------------------
@@ -65,10 +82,7 @@ ConditionTests.cpp:<line number>: FAILED:
 with expansion:
   false
 
-ConditionTests.cpp:<line number>: FAILED:
-  CHECK_FALSE( true )
-
 ===============================================================================
-test cases:  4 | 3 passed | 1 failed
-assertions: 10 | 6 passed | 4 failed
+test cases:  5 | 3 passed | 2 failed
+assertions: 11 | 7 passed | 4 failed
 
diff --git a/projects/SelfTest/Baselines/junit.sw.approved.txt b/projects/SelfTest/Baselines/junit.sw.approved.txt
index 41cfb464..2bec8e6b 100644
--- a/projects/SelfTest/Baselines/junit.sw.approved.txt
+++ b/projects/SelfTest/Baselines/junit.sw.approved.txt
@@ -1,9 +1,14 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <testsuitesspanner>
-  <testsuite name="<exe-name>" errors="13" failures="76" tests="958" hostname="tbd" time="{duration}" timestamp="{iso8601-timestamp}">
+  <testsuite name="<exe-name>" errors="13" failures="77" tests="960" hostname="tbd" time="{duration}" timestamp="{iso8601-timestamp}">
     <testcase classname="global" name="# A test name that starts with a #" time="{duration}"/>
     <testcase classname="global" name="#542" time="{duration}"/>
     <testcase classname="global" name="#809" time="{duration}"/>
+    <testcase classname="global" name="#835 -- errno should not be touched by Catch" time="{duration}">
+      <failure message="1 == 0" type="CHECK">
+MiscTests.cpp:<line number>
+      </failure>
+    </testcase>
     <testcase classname="global" name="'Not' checks that should fail" time="{duration}">
       <failure message="false != false" type="CHECK">
 ConditionTests.cpp:<line number>
diff --git a/projects/SelfTest/Baselines/xml.sw.approved.txt b/projects/SelfTest/Baselines/xml.sw.approved.txt
index ab6ab08b..f77b7e52 100644
--- a/projects/SelfTest/Baselines/xml.sw.approved.txt
+++ b/projects/SelfTest/Baselines/xml.sw.approved.txt
@@ -50,6 +50,25 @@
       </Expression>
       <OverallResult success="true"/>
     </TestCase>
+    <TestCase name="#835 -- errno should not be touched by Catch" filename="projects/<exe-name>/MiscTests.cpp" >
+      <Expression success="false" type="CHECK" filename="projects/<exe-name>/MiscTests.cpp" >
+        <Original>
+          f() == 0
+        </Original>
+        <Expanded>
+          1 == 0
+        </Expanded>
+      </Expression>
+      <Expression success="true" type="REQUIRE" filename="projects/<exe-name>/MiscTests.cpp" >
+        <Original>
+          (*__errno_location ()) == 1
+        </Original>
+        <Expanded>
+          1 == 1
+        </Expanded>
+      </Expression>
+      <OverallResult success="false"/>
+    </TestCase>
     <TestCase name="'Not' checks that should fail" tags="[.][failing][hide]" filename="projects/<exe-name>/ConditionTests.cpp" >
       <Expression success="false" type="CHECK" filename="projects/<exe-name>/ConditionTests.cpp" >
         <Original>
@@ -9988,7 +10007,7 @@ spanner      <OverallResult success="true"/>
       </Section>
       <OverallResult success="true"/>
     </TestCase>
-    <OverallResults successes="851" failures="89" expectedFailures="18"/>
+    <OverallResults successes="852" failures="90" expectedFailures="18"/>
   </Group>
-  <OverallResults successes="851" failures="88" expectedFailures="18"/>
+  <OverallResults successes="852" failures="89" expectedFailures="18"/>
 </Catch>
diff --git a/projects/SelfTest/MiscTests.cpp b/projects/SelfTest/MiscTests.cpp
index 88a524f8..e98b2630 100644
--- a/projects/SelfTest/MiscTests.cpp
+++ b/projects/SelfTest/MiscTests.cpp
@@ -16,6 +16,7 @@
 #include "../include/internal/catch_xmlwriter.hpp"
 
 #include <iostream>
+#include <cerrno>
 
 TEST_CASE( "random SECTION tests", "[.][sections][failing]" )
 {
@@ -393,3 +394,14 @@ TEST_CASE( "This test 'should' fail but doesn't", "[.][failing][!shouldfail]" )
 TEST_CASE( "# A test name that starts with a #" ) {
     SUCCEED( "yay" );
 }
+
+
+static int f() {
+    return 1;
+}
+
+TEST_CASE( "#835 -- errno should not be touched by Catch" ) {
+  errno = 1;
+  CHECK(f() == 0);
+  REQUIRE(errno == 1); // Check that f() doesn't touch errno.    
+}