diff --git a/Makefile b/Makefile
index 878ae21..a2d445c 100644
--- a/Makefile
+++ b/Makefile
@@ -27,7 +27,8 @@ HDR=ebind.h edef.h efunc.h epath.h estruct.h evar.h
 # DO NOT ADD OR MODIFY ANY LINES ABOVE THIS -- make source creates them
 
 CC=gcc
-CFLAGS=-O2 -Wall
+WARNINGS=-Wall -Wstrict-prototypes
+CFLAGS=-O2 $(WARNINGS)
 #CC=c89 +O3			# HP
 #CFLAGS= -D_HPUX_SOURCE -DSYSV
 #CFLAGS=-O4 -DSVR4		# Sun
diff --git a/edef.h b/edef.h
index c803016..9765888 100644
--- a/edef.h
+++ b/edef.h
@@ -110,7 +110,7 @@ extern struct buffer *bheadp;		/* Head of list of buffers      */
 extern struct buffer *blistp;		/* Buffer for C-X C-B           */
 
 extern struct buffer *bfind(char *bname, int cflag, int bflag); /* Lookup a buffer by name      */
-extern window_t *wpopup();	/* Pop up window creation       */
+extern window_t *wpopup(void);	/* Pop up window creation       */
 extern LINE *lalloc(int);	/* Allocate a line              */
 extern char sres[NBUFN];	/* current screen resolution    */
 extern char pat[];		/* Search pattern               */
diff --git a/eval.c b/eval.c
index 1ab2b64..fa25080 100644
--- a/eval.c
+++ b/eval.c
@@ -184,6 +184,7 @@ char *gtusr(char *vname)
 	return (errorm);
 }
 
+extern char *getkill(void);
 
 /*
  * gtenv()
@@ -193,7 +194,6 @@ char *gtusr(char *vname)
 char *gtenv(char *vname)
 {
 	int vnum;	/* ordinal number of var refrenced */
-	char *getkill();
 
 	/* scan the list, looking for the referenced name */
 	for (vnum = 0; vnum < NEVARS; vnum++)
diff --git a/isearch.c b/isearch.c
index fdfbfc2..8932baa 100644
--- a/isearch.c
+++ b/isearch.c
@@ -33,7 +33,7 @@ static int echo_char(int c, int col);
 
 /* A couple of "own" variables for re-eat */
 
-static int (*saved_get_char) ();	/* Get character routine */
+static int (*saved_get_char) (void);	/* Get character routine */
 static int eaten_char = -1;		/* Re-eaten char */
 
 /* A couple more "own" variables for the command string */
diff --git a/search.c b/search.c
index d35f7e9..65ccaf9 100644
--- a/search.c
+++ b/search.c
@@ -1368,6 +1368,8 @@ static int mceq(int bc, MC *mt)
 	return (result);
 }
 
+extern BITMAP clearbits(void);
+
 /*
  * cclmake -- create the bitmap for the character class.
  *	ppatptr is left pointing to the end-of-character-class character,
@@ -1375,7 +1377,6 @@ static int mceq(int bc, MC *mt)
  */
 static int cclmake(char **ppatptr, MC *mcptr)
 {
-	BITMAP clearbits();
 	BITMAP bmap;
 	char *patptr;
 	int pchr, ochr;
diff --git a/spawn.c b/spawn.c
index 856de23..d4239c6 100644
--- a/spawn.c
+++ b/spawn.c
@@ -27,7 +27,7 @@ extern short iochan;		/* In "termio.c"        */
 #include        <signal.h>
 #ifdef SIGWINCH
 extern int chg_width, chg_height;
-extern void sizesignal();
+extern void sizesignal(int);
 #endif
 #endif