diff --git a/deps/Makefile b/deps/Makefile
index 3def5bac7..824dd1a06 100644
--- a/deps/Makefile
+++ b/deps/Makefile
@@ -30,7 +30,7 @@ endif
 ### detect compiler support for c++11/17
 CPLUSPLUS := $(shell ${CC} -std=c++17 -dM -E -x c++ /dev/null 2>/dev/null | grep -F __cplusplus | egrep -o '[0-9]{6}L')
 ifneq ($(CPLUSPLUS),201703L)
-	CPLUSPLUS := $(shell ${CC} -std=c++11 -dM -E -x c++ /dev/null 2>/dev/null| grep -F __cplusplus | grep -o '[0-9]{6}L')
+	CPLUSPLUS := $(shell ${CC} -std=c++11 -dM -E -x c++ /dev/null 2>/dev/null| grep -F __cplusplus | egrep -o '[0-9]{6}L')
 ifneq ($(CPLUSPLUS),201103L)
     $(error Compiler must support at least c++11)
 endif
diff --git a/src/Makefile b/src/Makefile
index 656df70db..093f303be 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -105,9 +105,9 @@ endif
 
 
 ### detect compiler support for c++11/17
-CPLUSPLUS := $(shell ${CC} -std=c++17 -dM -E -x c++ /dev/null 2>/dev/null | grep -F __cplusplus | egrep -o '[0-9]{6}')
+CPLUSPLUS := $(shell ${CC} -std=c++17 -dM -E -x c++ /dev/null 2>/dev/null | grep -F __cplusplus | egrep -o '[0-9]{6}L')
 ifneq ($(CPLUSPLUS),201703L)
-	CPLUSPLUS := $(shell ${CC} -std=c++11 -dM -E -x c++ /dev/null 2>/dev/null| grep -F __cplusplus | egrep -o '[0-9]{6}')
+	CPLUSPLUS := $(shell ${CC} -std=c++11 -dM -E -x c++ /dev/null 2>/dev/null| grep -F __cplusplus | egrep -o '[0-9]{6}L')
 ifneq ($(CPLUSPLUS),201103L)
     $(error Compiler must support at least c++11)
 endif
diff --git a/test/tap/tap/Makefile b/test/tap/tap/Makefile
index d0b429467..831948a77 100644
--- a/test/tap/tap/Makefile
+++ b/test/tap/tap/Makefile
@@ -38,9 +38,9 @@ LIBPROXYSQLAR := $(PROXYSQL_LDIR)/libproxysql.a
 IDIRS := -I$(PROXYSQL_IDIR) -I$(JSON_IDIR) -I$(MARIADB_IDIR) -I${CURL_IDIR} -I${SQLITE3_IDIR} -I$(DOTENV_IDIR)
 
 ### detect compiler support for c++11/17
-CPLUSPLUS := $(shell ${CC} -std=c++17 -dM -E -x c++ /dev/null 2>/dev/null | grep -F __cplusplus | egrep -o '[0-9]{6}')
+CPLUSPLUS := $(shell ${CC} -std=c++17 -dM -E -x c++ /dev/null 2>/dev/null | grep -F __cplusplus | egrep -o '[0-9]{6}L')
 ifneq ($(CPLUSPLUS),201703L)
-	CPLUSPLUS := $(shell ${CC} -std=c++11 -dM -E -x c++ /dev/null 2>/dev/null| grep -F __cplusplus | egrep -o '[0-9]{6}')
+	CPLUSPLUS := $(shell ${CC} -std=c++11 -dM -E -x c++ /dev/null 2>/dev/null| grep -F __cplusplus | egrep -o '[0-9]{6}L')
 ifneq ($(CPLUSPLUS),201103L)
     $(error Compiler must support at least c++11)
 endif
diff --git a/test/tap/tests/Makefile b/test/tap/tests/Makefile
index 4cce74fd2..f4f29da9c 100644
--- a/test/tap/tests/Makefile
+++ b/test/tap/tests/Makefile
@@ -131,9 +131,9 @@ ifeq ($(UNAME_S),Linux)
 endif
 
 ### detect compiler support for c++11/17
-CPLUSPLUS := $(shell ${CC} -std=c++17 -dM -E -x c++ /dev/null 2>/dev/null | grep -F __cplusplus | egrep -o '[0-9]{6}')
+CPLUSPLUS := $(shell ${CC} -std=c++17 -dM -E -x c++ /dev/null 2>/dev/null | grep -F __cplusplus | egrep -o '[0-9]{6}L')
 ifneq ($(CPLUSPLUS),201703L)
-	CPLUSPLUS := $(shell ${CC} -std=c++11 -dM -E -x c++ /dev/null 2>/dev/null| grep -F __cplusplus | egrep -o '[0-9]{6}')
+	CPLUSPLUS := $(shell ${CC} -std=c++11 -dM -E -x c++ /dev/null 2>/dev/null| grep -F __cplusplus | egrep -o '[0-9]{6}L')
 ifneq ($(CPLUSPLUS),201103L)
     $(error Compiler must support at least c++11)
 endif
diff --git a/test/tap/tests_with_deps/deprecate_eof_support/Makefile b/test/tap/tests_with_deps/deprecate_eof_support/Makefile
index 23be8c731..0c7948a8c 100644
--- a/test/tap/tests_with_deps/deprecate_eof_support/Makefile
+++ b/test/tap/tests_with_deps/deprecate_eof_support/Makefile
@@ -86,9 +86,9 @@ TEST_MYSQL_EDIR := $(TEST_MYSQL_PATH)/libbinlogevents/export
 TEST_MYSQL_LDIR := $(TEST_MYSQL_PATH)/libmysql
 
 ### detect compiler support for c++11/17
-CPLUSPLUS := $(shell ${CC} -std=c++17 -dM -E -x c++ /dev/null 2>/dev/null | grep -F __cplusplus | egrep -o '[0-9]{6}')
+CPLUSPLUS := $(shell ${CC} -std=c++17 -dM -E -x c++ /dev/null 2>/dev/null | grep -F __cplusplus | egrep -o '[0-9]{6}L')
 ifneq ($(CPLUSPLUS),201703L)
-	CPLUSPLUS := $(shell ${CC} -std=c++11 -dM -E -x c++ /dev/null 2>/dev/null| grep -F __cplusplus | egrep -o '[0-9]{6}')
+	CPLUSPLUS := $(shell ${CC} -std=c++11 -dM -E -x c++ /dev/null 2>/dev/null| grep -F __cplusplus | egrep -o '[0-9]{6}L')
 ifneq ($(CPLUSPLUS),201103L)
     $(error Compiler must support at least c++11)
 endif