diff --git a/scripts/configure.in b/scripts/configure.in
index 608c5d43..11c37324 100644
--- a/scripts/configure.in
+++ b/scripts/configure.in
@@ -196,6 +196,17 @@ then
     AC_DEFINE(HAVE___VA_COPY, 1, [Define if we have __va_copy])
 fi
 
+dnl Control assertions in codebase from configure
+AC_ARG_ENABLE(assertions,
+[  --enable-assertions          build with fatal assertions enabled],
+[],
+[enable_assertions=no])
+
+NDEBUG_defs="-DNDEBUG"
+if test "x$enable_assertions" = "xyes" ; then
+   NDEBUG_defs=""
+fi
+
 dnl Allow file compression (zlib) to be disabled
 AC_ARG_ENABLE(compression,
 [  --disable-compression        disable file compression],
@@ -1812,6 +1823,7 @@ AC_SUBST(SCRIPTS)
 AC_SUBST(extra_libs)
 AC_SUBST(extra_defs)
 AC_SUBST(stub_defs)
+AC_SUBST(NDEBUG_defs)
 AC_SUBST(ld_extra_libs)
 AC_SUBST(ld_extra_objs)
 AC_SUBST(top_extra_libs)
diff --git a/scripts/defs.mak.in b/scripts/defs.mak.in
index 452854a1..69a38021 100755
--- a/scripts/defs.mak.in
+++ b/scripts/defs.mak.in
@@ -94,9 +94,9 @@ CXX		       = @CXX@
 CPPFLAGS               = -I${MAGICDIR} @CPPFLAGS@
 DFLAGS_MAGICVERSION    = -DMAGIC_VERSION=\"${MAGIC_VERSION}\" -DMAGIC_REVISION=\"${MAGIC_REVISION}\" -DMAGIC_COMMIT=\"${MAGIC_COMMIT}\" "-DMAGIC_BUILDDATE=\"${MAGIC_BUILDDATE}\""
 DFLAGS                 = @extra_defs@ @stub_defs@ @DEFS@ ${DFLAGS_MAGICVERSION} -DGCORE=\"@GCORE@\"
-DFLAGS		      += -DSHDLIB_EXT=\"@SHDLIB_EXT@\" -DNDEBUG
+DFLAGS		      += -DSHDLIB_EXT=\"@SHDLIB_EXT@\" @NDEBUG_defs@
 DFLAGS_NOSTUB	       = @extra_defs@             @DEFS@ ${DFLAGS_MAGICVERSION} -DGCORE=\"@GCORE@\"
-DFLAGS_NOSTUB	      += -DSHDLIB_EXT=\"@SHDLIB_EXT@\" -DNDEBUG
+DFLAGS_NOSTUB	      += -DSHDLIB_EXT=\"@SHDLIB_EXT@\" @NDEBUG_defs@
 CFLAGS                 = @CFLAGS@ @SHLIB_CFLAGS@ @INC_SPECS@
 
 READLINE_DEFS          = @rl_defs@
@@ -107,7 +107,7 @@ DEPEND_FLAG	       = @DEPEND_FLAG@
 EXEEXT		       = @EXEEXT@
 
 GR_CFLAGS              = @X_CFLAGS@ @gr_cflags@
-GR_DFLAGS	       = @gr_dflags@ -DNDEBUG
+GR_DFLAGS	       = @gr_dflags@
 GR_LIBS                = @X_LIBS@ @X_PRE_LIBS@ @gr_libs@ @X_EXTRA_LIBS@
 GR_SRCS                = @gr_srcs@
 GR_HELPER_SRCS         = @gr_hsrcs@