diff --git a/nmap-update/configure b/nmap-update/configure
index 138ae2ead..c7e6ce1c3 100755
--- a/nmap-update/configure
+++ b/nmap-update/configure
@@ -3028,6 +3028,11 @@ else
 fi
 
 
+# GCC-specific flags
+if test -n "$GCC"; then
+  CFLAGS="$CFLAGS -Wall"
+fi
+
 
   apr_found="no"
 
diff --git a/nmap-update/configure.ac b/nmap-update/configure.ac
index 5b7d07727..cf6bda418 100644
--- a/nmap-update/configure.ac
+++ b/nmap-update/configure.ac
@@ -12,6 +12,11 @@ AC_PROG_CC
 AC_PROG_INSTALL
 AC_PATH_TOOL([STRIP], [strip], [/bin/true])
 
+# GCC-specific flags
+if test -n "$GCC"; then
+  CFLAGS="$CFLAGS -Wall"
+fi
+
 APR_FIND_APR(, , 1, 1)
 if test "$apr_found" = "no"; then
   AC_MSG_ERROR([libapr is required to build nmap-update.])