diff --git a/.Rbuildignore b/.Rbuildignore
index a3193d4f25..2b3483fa0e 100644
--- a/.Rbuildignore
+++ b/.Rbuildignore
@@ -15,6 +15,7 @@
 ^NEWS\.0\.md$
 ^README\.md$
 ^_pkgdown\.yml$
+^src/Makevars$
 
 ^\.RData$
 ^\.Rhistory$
diff --git a/.gitignore b/.gitignore
index ce159ee5f6..35a25bc087 100644
--- a/.gitignore
+++ b/.gitignore
@@ -9,6 +9,7 @@ Rplots.pdf
 *-Ex.R
 data.table_*.tar.gz
 data.table.Rcheck
+src/Makevars
 
 # Emacs IDE files
 .emacs.desktop
diff --git a/NEWS.md b/NEWS.md
index 4a0033fcfa..1cfad0b453 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -8,6 +8,8 @@
 
 1. `DT[, {...; .(A,B)}]` (i.e. when `.()` is the final item of a multi-statement `{...}`) now auto-names the columns `A` and `B` (just like `DT[, .(A,B)]`) rather than `V1` and `V2`, [#2478](https://github.com/Rdatatable/data.table/issues/2478) [#609](https://github.com/Rdatatable/data.table/issues/609). Similarly, `DT[, if (.N>1) .(B), by=A]` now auto-names the column `B` rather than `V1`. Explicit names are unaffected; e.g. `DT[, {... y= ...; .(A=C+y)}, by=...]` named the column `A` before, and still does. Thanks also to @renkun-ken for his go-first strong testing which caught an issue not caught by the test suite or by revdep testing, related to NULL being the last item, [#4061](https://github.com/Rdatatable/data.table/issues/4061).
 
+2. Compiler support for OpenMP is now detected during installation, which allows data.table to compile even if the users' toolchain differs from CRANs, as is common on macOS, [#2161](https://github.com/Rdatatable/data.table/issues/2161). Thanks @jimhester for the PR.
+
 ## BUG FIXES
 
 ## NOTES
diff --git a/cleanup b/cleanup
new file mode 100755
index 0000000000..3c020d3881
--- /dev/null
+++ b/cleanup
@@ -0,0 +1,2 @@
+#!/bin/sh
+rm -f src/Makevars
diff --git a/configure b/configure
index 96fc844a18..b20ba04b4b 100755
--- a/configure
+++ b/configure
@@ -50,5 +50,27 @@ fi
 
 version=`pkg-config --modversion zlib`
 echo "zlib ${version} is available ok"
-exit 0
 
+# Find R compilers
+CC=`${R_HOME}/bin/R CMD config CC`
+CFLAGS=`${R_HOME}/bin/R CMD config CFLAGS`
+CPPFLAGS=`${R_HOME}/bin/R CMD config CPPFLAGS`
+
+# Test if we have a OPENMP compatible compiler
+echo "#include <omp.h>\nint main () { return omp_get_num_threads (); }" | ${CC} ${CPPFLAGS} ${PKG_CFLAGS} ${CFLAGS} ${SHLIB_OPENMP_CFLAGS} -E -xc - >/dev/null 2>&1 || R_NO_OPENMP=1;
+
+# Write to Makevars
+if [ $R_NO_OPENMP ]; then
+  echo "*** OpenMP not supported! data.table uses OpenMP to automatically"
+  echo "***   parallelize operations like sorting, grouping, file reading, etc."
+  echo "*** For details on how to install the necessary toolchains on your OS see:"
+  echo "***   https://github.com/Rdatatable/data.table/wiki/Installation"
+  echo "*** Continuing installation without OpenMP support..."
+  sed -e "s|@openmp_cflags@||" src/Makevars.in > src/Makevars
+else
+  echo "OpenMP supported"
+  sed -e "s|@openmp_cflags@|\$(SHLIB_OPENMP_CFLAGS)|" src/Makevars.in > src/Makevars
+fi
+
+
+exit 0
diff --git a/src/Makevars b/src/Makevars.in
similarity index 70%
rename from src/Makevars
rename to src/Makevars.in
index e8e586004c..8f20d70560 100644
--- a/src/Makevars
+++ b/src/Makevars.in
@@ -1,9 +1,6 @@
-
-PKG_CFLAGS = $(SHLIB_OPENMP_CFLAGS)
-PKG_LIBS = $(SHLIB_OPENMP_CFLAGS) -lz
+PKG_CFLAGS = @openmp_cflags@
+PKG_LIBS = @openmp_cflags@ -lz
 
 all: $(SHLIB)
 	mv $(SHLIB) datatable$(SHLIB_EXT)
 	if [ "$(OS)" != "Windows_NT" ] && [ `uname -s` = 'Darwin' ]; then install_name_tool -id datatable$(SHLIB_EXT) datatable$(SHLIB_EXT); fi
-
-
diff --git a/src/Makevars.win b/src/Makevars.win
new file mode 100644
index 0000000000..3ea29da12d
--- /dev/null
+++ b/src/Makevars.win
@@ -0,0 +1,5 @@
+PKG_CFLAGS = $(SHLIB_OPENMP_CFLAGS)
+PKG_LIBS = $(SHLIB_OPENMP_CFLAGS) -lz
+
+all: $(SHLIB)
+	mv $(SHLIB) datatable$(SHLIB_EXT)