diff --git a/CMakeLists.txt b/CMakeLists.txt
index abb900592a..2dc30a21d4 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -25,14 +25,13 @@ endif()
 # Command line options
 #===============================================================================
 
-option(openmp   "Enable shared-memory parallelism with OpenMP"   OFF)
+option(openmp   "Enable shared-memory parallelism with OpenMP"   ON)
 option(profile  "Compile with profiling flags"                   OFF)
 option(debug    "Compile with debug flags"                       OFF)
 option(optimize "Turn on all compiler optimization flags"        OFF)
 option(coverage "Compile with coverage analysis flags"           OFF)
 option(mpif08   "Use Fortran 2008 MPI interface"                 OFF)
 
-
 # Maximum number of nested coordinates levels
 set(maxcoord 10 CACHE STRING "Maximum number of nested coordinate levels")
 add_definitions(-DMAX_COORD=${maxcoord})
@@ -108,9 +107,11 @@ if(CMAKE_Fortran_COMPILER_ID STREQUAL GNU)
   endif()
 
   # GCC compiler options
-  list(APPEND f90flags -cpp -std=f2008 -fbacktrace)
-  list(APPEND cflags -cpp -std=c99)
+  list(APPEND f90flags -cpp -std=f2008 -fbacktrace -O2)
+  list(APPEND cflags -cpp -std=c99 -O2)
   if(debug)
+    list(REMOVE_ITEM f90flags -O2)
+    list(REMOVE_ITEM cflags -O2)
     list(APPEND f90flags -g -Wall -pedantic -fbounds-check
       -ffpe-trap=invalid,overflow,underflow)
     list(APPEND cflags -g -Wall -pedantic -fbounds-check)
@@ -122,6 +123,8 @@ if(CMAKE_Fortran_COMPILER_ID STREQUAL GNU)
     list(APPEND ldflags -pg)
   endif()
   if(optimize)
+    list(REMOVE_ITEM f90flags -O2)
+    list(REMOVE_ITEM cflags -O2)
     list(APPEND f90flags -O3)
     list(APPEND cflags -O3)
   endif()
@@ -142,8 +145,8 @@ elseif(CMAKE_Fortran_COMPILER_ID STREQUAL Intel)
   list(APPEND cflags -std=c99)
   if(debug)
     list(APPEND f90flags -g -warn -ftrapuv -fp-stack-check
-      "-check all" -fpe0)
-    list(APPEND cflags -g -w3 -ftrapuv -fp-stack-check)
+      "-check all" -fpe0 -O0)
+    list(APPEND cflags -g -w3 -ftrapuv -fp-stack-check -O0)
     list(APPEND ldflags -g)
   endif()
   if(profile)
@@ -182,7 +185,8 @@ elseif(CMAKE_Fortran_COMPILER_ID STREQUAL XL)
   list(APPEND f90flags -O2)
   add_definitions(-DNO_F2008)
   if(debug)
-    list(APPEND f90flags -g -C -qflag=i:i -u)
+    list(REMOVE_ITEM f90flags -O2)
+    list(APPEND f90flags -g -C -qflag=i:i -u -O0)
     list(APPEND ldflags -g)
   endif()
   if(profile)
@@ -190,6 +194,7 @@ elseif(CMAKE_Fortran_COMPILER_ID STREQUAL XL)
     list(APPEND ldflags -p)
   endif()
   if(optimize)
+    list(REMOVE_ITEM f90flags -O2)
     list(APPEND f90flags -O3)
   endif()
   if(openmp)
@@ -207,6 +212,11 @@ elseif(CMAKE_Fortran_COMPILER_ID STREQUAL Cray)
 
 endif()
 
+# Show flags being used
+message(STATUS "Fortran flags: ${f90flags}")
+message(STATUS "C flags: ${cflags}")
+message(STATUS "Linker flags: ${ldflags}")
+
 #===============================================================================
 # git SHA1 hash
 #===============================================================================
diff --git a/docs/source/usersguide/install.rst b/docs/source/usersguide/install.rst
index 9d16b51814..bf7ed5cb0b 100644
--- a/docs/source/usersguide/install.rst
+++ b/docs/source/usersguide/install.rst
@@ -231,7 +231,7 @@ optimize
 
 openmp
   Enables shared-memory parallelism using the OpenMP API. The Fortran compiler
-  being used must support OpenMP.
+  being used must support OpenMP. (Default: on)
 
 coverage
   Compile and link code instrumented for coverage analysis. This is typically
diff --git a/tests/run_tests.py b/tests/run_tests.py
index f0ecd82916..2d9112e92e 100755
--- a/tests/run_tests.py
+++ b/tests/run_tests.py
@@ -184,8 +184,8 @@ class Test(object):
             build_str += "-Ddebug=ON "
         if self.optimize:
             build_str += "-Doptimize=ON "
-        if self.openmp:
-            build_str += "-Dopenmp=ON "
+        if not self.openmp:
+            build_str += "-Dopenmp=OFF "
         if self.coverage:
             build_str += "-Dcoverage=ON "
         self.build_opts = build_str