--- a/configure.in
+++ b/configure.in
@@ -8,8 +8,6 @@
 AM_CONFIG_HEADER(config.h)
 
 AC_ISC_POSIX
-CFLAGS=""
-AC_SUBST(CFLAGS)
 AC_PROG_CC
 AM_PROG_CC_STDC
 AC_HEADER_STDC
@@ -21,6 +19,10 @@
 
 
 dnl Checks for libraries.
+dnl Check for libm for fmod()
+AC_SEARCH_LIBS([fmod], [m], [], [
+	AC_MSG_ERROR([unable to find the fmod() function])
+])
 
 
 dnl Checks for header files.
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -7,10 +7,6 @@
 INCLUDES = \
 	$(GTK_CFLAGS)
 
-AM_CFLAGS =\
-	 -Wall\
-	 -O3
-
 bin_PROGRAMS = euler
 
 euler_SOURCES = \