diff --git a/ChangeLog b/ChangeLog
index 2cfba9798..109aaa601 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -9,6 +9,8 @@
     easier comparison by month of tasks added versus completed and deleted.
   + "task version" command now reports unrecognized configuration variables,
     which may be spelling mistakes or deprecated variables.
+  + "configure --enable-debug" now supported to suppress compiler optimization
+    to allow debugging.
 
 ------ old releases ------------------------------
 
diff --git a/configure.ac b/configure.ac
index 120a41cc0..364500f72 100644
--- a/configure.ac
+++ b/configure.ac
@@ -3,6 +3,29 @@
 
 AC_PREREQ(2.61)
 AC_INIT(task, 1.5.0, bugs@beckingham.net)
+
+
+CFLAGS="${CFLAGS=}"
+CXXFLAGS="${CXXFLAGS=}"
+# this macro is used to get the arguments supplied
+# to the configure script (./configure --enable-debug)
+# Check if we have enable debug support.
+AC_MSG_CHECKING(whether to enable debugging)
+debug_default="yes"
+AC_ARG_ENABLE(debug, [  --enable-debug=[no/yes] turn on debugging
+                       [default=$debug_default]],, enable_debug=$debug_default)
+# Yes, shell scripts can be used
+if test "x$enable_debug" = "xyes"; then
+CFLAGS="$CFLAGS -Wall -pedantic -ggdb3 -DDEBUG"
+CXXFLAGS="$CFLAGS -Wall -pedantic -ggdb3 -DDEBUG"
+AC_MSG_RESULT(yes)
+else
+CFLAGS="$CFLAGS -O3"
+CXXFLAGS="$CFLAGS -O3"
+AC_MSG_RESULT(no)
+fi
+
+
 AM_INIT_AUTOMAKE
 AC_CONFIG_SRCDIR([src/task.cpp])
 AC_CONFIG_HEADER([auto.h])
@@ -12,6 +35,8 @@ AC_PROG_CXX
 AC_PROG_CC
 AC_LANG(C++)
 
+AC_SUBST(CFLAGS)
+
 # Checks for libraries.
 AC_CHECK_LIB(ncurses,initscr)
 AC_CHECK_LIB(ncurses,endwin)
diff --git a/html/task.html b/html/task.html
index cd398f0a3..3a4bfd7f2 100644
--- a/html/task.html
+++ b/html/task.html
@@ -102,6 +102,8 @@
                       easier comparison by month of tasks added versus completed and deleted.
                   <li>"task version" command now reports unrecognized configuration variables,
                       which may be spelling mistakes or deprecated variables.
+                  <li>"configure --enable-debug" now supported to suppress compiler optimization
+                      to allow debugging.
                 </ul>
 
                 <p>
diff --git a/src/Makefile.am b/src/Makefile.am
index eae651e2b..2e92854a2 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -1,3 +1,2 @@
 bin_PROGRAMS = task
 task_SOURCES = Config.cpp Date.cpp T.cpp TDB.cpp Table.cpp Grid.cpp color.cpp parse.cpp task.cpp command.cpp report.cpp util.cpp text.cpp rules.cpp Config.h Date.h T.h TDB.h Table.h Grid.h color.h task.h
-AM_CPPFLAGS = -Wall -pedantic -ggdb3 -fno-rtti
diff --git a/src/Makefile.in b/src/Makefile.in
index 120185c41..c8ca21f5f 100644
--- a/src/Makefile.in
+++ b/src/Makefile.in
@@ -155,7 +155,6 @@ target_alias = @target_alias@
 top_builddir = @top_builddir@
 top_srcdir = @top_srcdir@
 task_SOURCES = Config.cpp Date.cpp T.cpp TDB.cpp Table.cpp Grid.cpp color.cpp parse.cpp task.cpp command.cpp report.cpp util.cpp text.cpp rules.cpp Config.h Date.h T.h TDB.h Table.h Grid.h color.h task.h
-AM_CPPFLAGS = -Wall -pedantic -ggdb3 -fno-rtti
 all: all-am
 
 .SUFFIXES: