diff --git a/CMakeLists.txt b/CMakeLists.txt
index fd006abc..404c6e88 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -22,6 +22,16 @@ set(CMAKE_OSX_DEPLOYMENT_TARGET 10.7)
 # only relevant for building shared libs but let's set it regardless
 set(CMAKE_OSX_RPATH 1)
 
+# Set the C++ standard to C++98 to avoid compilation errors on GCC 6 (which
+# defaults to C++14).
+if(CMAKE_VERSION VERSION_LESS "3.1")
+  if(CMAKE_COMPILER_IS_GNUCXX)
+    set (CMAKE_CXX_FLAGS "--std=gnu++98 ${CMAKE_CXX_FLAGS}")
+  endif()
+else()
+  set (CMAKE_CXX_STANDARD 98)
+endif()
+
 project(SimGear)
 
 # read 'version' file into a variable (stripping any newlines or spaces)
diff --git a/simgear/canvas/ShivaVG/src/shPipeline.c b/simgear/canvas/ShivaVG/src/shPipeline.c
index 4eb2fd27..c3eb85cd 100644
--- a/simgear/canvas/ShivaVG/src/shPipeline.c
+++ b/simgear/canvas/ShivaVG/src/shPipeline.c
@@ -80,8 +80,12 @@ void updateBlendingStateGL(VGContext *c, int alphaIsOne)
 
   case VG_BLEND_SRC_OVER: default:
     glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
-    if (alphaIsOne) glDisable(GL_BLEND);
-    else glEnable(GL_BLEND); break;
+    if (alphaIsOne) {
+      glDisable(GL_BLEND);
+    } else {
+      glEnable(GL_BLEND);
+    }
+    break;
   };
 }
 
diff --git a/simgear/environment/metar.cxx b/simgear/environment/metar.cxx
index 4e96839c..5b497a05 100644
--- a/simgear/environment/metar.cxx
+++ b/simgear/environment/metar.cxx
@@ -648,10 +648,11 @@ bool SGMetar::scanWeather()
 	weather = pre + weather + post;
 	weather.erase(weather.length() - 1);
 	_weather.push_back(weather);
-    if( ! w.phenomena.empty() )
+    if( ! w.phenomena.empty() ) {
         _weather2.push_back( w );
-	_grpcount++;
-	return true;
+    }
+    _grpcount++;
+    return true;
 }
 
 
diff --git a/simgear/package/Root.cxx b/simgear/package/Root.cxx
index d6460ace..1aaf773c 100644
--- a/simgear/package/Root.cxx
+++ b/simgear/package/Root.cxx
@@ -384,7 +384,7 @@ void Root::refresh(bool aForce)
     CatalogList toRefresh;
     CatalogDict::iterator it = d->catalogs.begin();
     for (; it != d->catalogs.end(); ++it) {
-        int age = it->second->ageInSeconds();
+        unsigned int age = it->second->ageInSeconds();
         if (aForce || (age > maxAgeSeconds())) {
             toRefresh.push_back(it->second);
         }
diff --git a/simgear/sound/sample_openal.cxx b/simgear/sound/sample_openal.cxx
index 95a60775..3bb124bc 100644
--- a/simgear/sound/sample_openal.cxx
+++ b/simgear/sound/sample_openal.cxx
@@ -260,5 +260,8 @@ SGPath SGSoundSample::file_path() const
 
 void SGSoundSample::free_data()
 {
-   if ( _data != NULL ) free( _data ); _data = NULL;
+   if ( _data != NULL ) {
+     free( _data );
+   }
+   _data = NULL;
 }