diff --git a/commands/CmdSubrs.c b/commands/CmdSubrs.c
index 9d42ae66..d3a5c7a3 100644
--- a/commands/CmdSubrs.c
+++ b/commands/CmdSubrs.c
@@ -396,10 +396,10 @@ CmdParseLayers(
 #define LN_CONNECT	5
     static struct
     {
-	char *layer_name;
+	const char *layer_name;
 	int layer_value;
     }
-    special[] =
+    const special[] =
     {
 	{"$",		LN_DOLLAR},
 	{"*",		LN_ALL},
@@ -439,7 +439,7 @@ CmdParseLayers(
 	type = DBTechNameTypes(name, &newmask);
 	if (type == -2)
 	{
-	    which = LookupStruct(name, (LookupTable *) special, sizeof special[0]);
+	    which = LookupStruct(name, (const LookupTable *) special, sizeof special[0]);
 	    if (which >= 0)
 	    {
 		switch (special[which].layer_value)
diff --git a/debug/debugFlags.c b/debug/debugFlags.c
index 9a71b392..9ae0caa7 100644
--- a/debug/debugFlags.c
+++ b/debug/debugFlags.c
@@ -214,7 +214,7 @@ DebugSet(clientID, argc, argv, value)
     dc = &debugClients[id];
     for (; argc-- > 0; argv++)
     {
-	n = LookupStruct(*argv, (LookupTable *) dc->dc_flags,
+	n = LookupStruct(*argv, (const LookupTable *) dc->dc_flags,
 			sizeof dc->dc_flags[0]);
 	if (n < 0)
 	{
diff --git a/drc/DRCtech.c b/drc/DRCtech.c
index 1391efdd..170fb037 100644
--- a/drc/DRCtech.c
+++ b/drc/DRCtech.c
@@ -1021,13 +1021,13 @@ DRCTechAddRule(sectionName, argc, argv)
 {
     int which, distance, mdist;
     char *fmt;
-    static struct
+    static const struct
     {
-	char	*rk_keyword;	/* Initial keyword */
+	const char *rk_keyword;	/* Initial keyword */
 	int	 rk_minargs;	/* Min # arguments */
 	int	 rk_maxargs;	/* Max # arguments */
 	int    (*rk_proc)();	/* Procedure implementing this keyword */
-	char	*rk_err;	/* Error message */
+	const char *rk_err;	/* Error message */
     } ruleKeys[] = {
 	{"angles",	 4,	4,	drcAngles,
     "layers 45|90 why"},
@@ -1080,7 +1080,7 @@ DRCTechAddRule(sectionName, argc, argv)
 
     drcRulesSpecified += 1;
 
-    which = LookupStruct(argv[0], (LookupTable *) ruleKeys, sizeof ruleKeys[0]);
+    which = LookupStruct(argv[0], (const LookupTable *) ruleKeys, sizeof ruleKeys[0]);
     if (which < 0)
     {
 	TechError("Bad DRC rule type \"%s\"\n", argv[0]);
diff --git a/extflat/EFread.c b/extflat/EFread.c
index 29742c72..5bdbe439 100644
--- a/extflat/EFread.c
+++ b/extflat/EFread.c
@@ -63,9 +63,9 @@ typedef enum
     SUBCAP, SUBSTRATE, TECH, TIMESTAMP, USE, VERSION, EXT_STYLE
 } Key;
 
-static struct
+static const struct
 {
-    char	*k_name;	/* Name of first token on line */
+    const char	*k_name;	/* Name of first token on line */
     Key 	 k_key;		/* Internal name for token of this type */
     int		 k_mintokens;	/* Min total # of tokens on line of this type */
 }
@@ -255,7 +255,7 @@ readfile:
     efReadLineNum = 0;
     while ((argc = efReadLine(&line, &size, inf, argv)) >= 0)
     {
-	n = LookupStruct(argv[0], (LookupTable *) keyTable, sizeof keyTable[0]);
+	n = LookupStruct(argv[0], (const LookupTable *) keyTable, sizeof keyTable[0]);
 	if (n < 0)
 	{
 	    efReadError("Unrecognized token \"%s\" (ignored)\n", argv[0]);
diff --git a/extract/ExtTech.c b/extract/ExtTech.c
index e1622319..0137f6ac 100644
--- a/extract/ExtTech.c
+++ b/extract/ExtTech.c
@@ -89,14 +89,14 @@ typedef enum
 
 typedef struct
 {
-    char	*k_name;
+    const char	*k_name;
     int		 k_key;
     int		 k_minargs;
     int		 k_maxargs;
-    char	*k_usage;
+    const char	*k_usage;
 } keydesc;
 
-static keydesc keyTable[] = {
+static const keydesc keyTable[] = {
     {"areacap",		AREAC,		3,	3,
 "types capacitance"},
 
@@ -202,7 +202,7 @@ static keydesc keyTable[] = {
 
 /* types are enumerated in extract.h */
 
-static keydesc devTable[] = {
+static const keydesc devTable[] = {
     {"mosfet",		DEV_MOSFET,		5,	10,
 "name gate-types src-types [drn-types] sub-types|None sub-node [gscap gccap]"},
 
@@ -1954,7 +1954,7 @@ ExtTechLine(sectionName, argc, argv)
     TileTypeBitMask near, far, ov, shield, subsTypes, idTypes;
     char *subsName, *transName, *cp, *endptr, *paramName;
     TileType s, t, r, o;
-    keydesc *kp, *dv;
+    const keydesc *kp, *dv;
     bool isLinear;
     HashEntry *he;
     EdgeCap *cnew;
@@ -1973,7 +1973,7 @@ ExtTechLine(sectionName, argc, argv)
 	return (TRUE);
     }
 
-    n = LookupStruct(argv[0], (LookupTable *) keyTable, sizeof keyTable[0]);
+    n = LookupStruct(argv[0], (const LookupTable *) keyTable, sizeof keyTable[0]);
     if (n < 0)
     {
 	TechError("Illegal keyword.  Legal keywords are:\n\t");
@@ -2343,7 +2343,7 @@ ExtTechLine(sectionName, argc, argv)
 
 	    /* Parse second argument for device type */
 
-	    n = LookupStruct(argv[1], (LookupTable *)devTable, sizeof devTable[0]);
+	    n = LookupStruct(argv[1], (const LookupTable *)devTable, sizeof devTable[0]);
 	    if (n < 0)
 	    {
 		TechError("Illegal device.  Legal devices are:\n\t");
diff --git a/extract/ExtTest.c b/extract/ExtTest.c
index 38b9c3fe..a95e657a 100644
--- a/extract/ExtTest.c
+++ b/extract/ExtTest.c
@@ -123,9 +123,9 @@ ExtractTest(w, cmd)
     typedef enum {  CLRDEBUG, CLRLENGTH, DRIVER, DUMP, INTERACTIONS,
 		    INTERCOUNT, EXTPARENTS, RECEIVER, SETDEBUG, SHOWDEBUG,
 		    SHOWPARENTS, SHOWTECH, STATS, STEP, TIME } cmdType;
-    static struct
+    static const struct
     {
-	char	*cmd_name;
+	const char *cmd_name;
 	cmdType	 cmd_val;
     } cmds[] = {
 	{"clrdebug",		CLRDEBUG},
@@ -163,7 +163,7 @@ ExtractTest(w, cmd)
 	return;
     }
 
-    n = LookupStruct(cmd->tx_argv[1], (LookupTable *) cmds, sizeof cmds[0]);
+    n = LookupStruct(cmd->tx_argv[1], (const LookupTable *) cmds, sizeof cmds[0]);
     if (n < 0)
     {
 	TxError("Unrecognized subcommand: %s\n", cmd->tx_argv[1]);
diff --git a/garouter/gaTest.c b/garouter/gaTest.c
index adc32ccf..3e6eca29 100644
--- a/garouter/gaTest.c
+++ b/garouter/gaTest.c
@@ -93,7 +93,7 @@ GATest(w, cmd)
 {
     int n;
     typedef enum { CLRDEBUG, SETDEBUG, SHOWDEBUG} cmdType;
-    static struct
+    static const struct
     {
 	char	*cmd_name;
 	cmdType	 cmd_val;
@@ -111,7 +111,7 @@ GATest(w, cmd)
 	goto badCmd;
     }
 
-    n = LookupStruct(cmd->tx_argv[1], (LookupTable *) cmds, sizeof cmds[0]);
+    n = LookupStruct(cmd->tx_argv[1], (const LookupTable *) cmds, sizeof cmds[0]);
     if (n < 0)
     {
 	TxError("Unrecognized subcommand: %s\n", cmd->tx_argv[1]);
diff --git a/grouter/grouteTest.c b/grouter/grouteTest.c
index 77a17cf2..fbdeb412 100644
--- a/grouter/grouteTest.c
+++ b/grouter/grouteTest.c
@@ -119,9 +119,9 @@ GlTest(w, cmd)
     typedef enum { CLRDEBUG, ONLYNET, SETDEBUG, SHOWDEBUG, SIDES } cmdType;
     Rect editArea;
     int n;
-    static struct
+    static const struct
     {
-	char	*cmd_name;
+	const char *cmd_name;
 	cmdType	 cmd_val;
     } cmds[] = {
 	{"clrdebug",		CLRDEBUG},
@@ -141,7 +141,7 @@ GlTest(w, cmd)
 	goto badCmd;
     }
 
-    n = LookupStruct(cmd->tx_argv[1], (LookupTable *) cmds, sizeof cmds[0]);
+    n = LookupStruct(cmd->tx_argv[1], (const LookupTable *) cmds, sizeof cmds[0]);
     if (n < 0)
     {
 	TxError("Unrecognized subcommand: %s\n", cmd->tx_argv[1]);
diff --git a/irouter/irCommand.c b/irouter/irCommand.c
index b91afa70..78d0685a 100644
--- a/irouter/irCommand.c
+++ b/irouter/irCommand.c
@@ -59,13 +59,13 @@ static MagWindow *irWindow;
 /* Subcommand table - declared here since its referenced before defined */
 typedef struct
 {
-    char	*sC_name;	/* name of iroute subcommand */
+    const char	*sC_name;	/* name of iroute subcommand */
     void	(*sC_proc)();	/* Procedure implementing this subcommand */
-    char 	*sC_commentString;	/* describes subcommand */
-    char 	*sC_usage;		/* command syntax */
+    const char 	*sC_commentString;	/* describes subcommand */
+    const char 	*sC_usage;		/* command syntax */
 
 } SubCmdTableE;
-extern SubCmdTableE irSubcommands[];
+extern const SubCmdTableE irSubcommands[];
 
 
 /*
@@ -105,9 +105,9 @@ irSetNoisyAutoInt(parm, valueS, file)
 
     /* special value Table */
 #define V_AUTOMATIC	-1
-    static struct
+    static const struct
     {
-	char	*sv_name;	/* name */
+	const char *sv_name;	/* name */
 	int	 sv_type;
     } specialValues[] = {
 	{"automatic",	V_AUTOMATIC},
@@ -122,7 +122,7 @@ irSetNoisyAutoInt(parm, valueS, file)
     	/* check if special value */
 	which = LookupStruct(
 	    valueS,
-	    (char **) specialValues,
+	    (const LookupTable *) specialValues,
 	    sizeof specialValues[0]);
 
 	if(which == -1)
@@ -674,9 +674,9 @@ FILE *file;
     /* special arg Table */
 #define SP_COMMAND	-1
 #define SP_DOT		-2
-    static struct
+    static const struct
     {
-	char	*sp_name;	/* name */
+	const char *sp_name;	/* name */
 	int	 sp_type;
     } specialArgs[] = {
 	{"command",	SP_COMMAND},
@@ -690,7 +690,7 @@ FILE *file;
 	/* check if special arg */
 	which = LookupStruct(
 	    s,
-	    (char **) specialArgs,
+	    (const LookupTable *) specialArgs,
 	    sizeof specialArgs[0]);
 
 	if(which == -1)
@@ -776,9 +776,9 @@ FILE *file;
  */
 
 /* Contact Parameter Table */
-static struct
+static const struct
 {
-    char	*cP_name;	/* name of parameter */
+    const char	*cP_name;	/* name of parameter */
 #ifdef MAGIC_WRAPPER
     Tcl_Obj	*(*cP_proc)();	/* Procedure processing this parameter */
 #else
@@ -938,7 +938,7 @@ irContactsCmd(w, cmd)
 	/* Lookup parameter name in contact parm table */
 	which = LookupStruct(
 	    cmd->tx_argv[3],
-	    (char **) cParms,
+	    (const LookupTable *) cParms,
 	    sizeof cParms[0]);
 
 	/* Process table lookup */
@@ -1001,7 +1001,7 @@ irContactsCmd(w, cmd)
 	    /* Lookup contact parameter name in table */
 	    which = LookupStruct(
 		cmd->tx_argv[3],
-		(char **) cParms,
+		(const LookupTable *) cParms,
 		sizeof cParms[0]);
 
 	    /* Process result of lookup */
@@ -1094,7 +1094,7 @@ irHelpCmd(w, cmd)
 	/* Lookup subcommand in table, and printed associated help info */
 	which = LookupStruct(
 	    cmd->tx_argv[2],
-	    (char **) irSubcommands,
+	    (const LookupTable *) irSubcommands,
 	    sizeof irSubcommands[0]);
 
         /* Process result of lookup */
@@ -1145,9 +1145,9 @@ irHelpCmd(w, cmd)
  */
 
 /* Layer Parameter Table */
-static struct
+static const struct
 {
-    char	*lP_name;	/* name of parameter */
+    const char	*lP_name;	/* name of parameter */
 #ifdef MAGIC_WRAPPER
     Tcl_Obj	*(*lP_proc)();	/* procedure processing this parameter */
 #else
@@ -1312,7 +1312,7 @@ irLayersCmd(w, cmd)
 	/* Lookup parameter name in layer parm table */
 	which = LookupStruct(
 	    cmd->tx_argv[3],
-	    (char **) lParms,
+	    (const LookupTable *) lParms,
 	    sizeof lParms[0]);
 
 	/* Process table lookup */
@@ -1377,7 +1377,7 @@ irLayersCmd(w, cmd)
 	    /* Lookup route layer parameter name in table */
 	    which = LookupStruct(
 		cmd->tx_argv[3],
-		(char **) lParms,
+		(const LookupTable *) lParms,
 		sizeof lParms[0]);
 
 	    /* Process result of lookup */
@@ -1742,9 +1742,9 @@ leaveClean:
  */
 
 /* Search Parameter Table */
-static struct
+static const struct
 {
-    char	*srP_name;	/* name of parameter */
+    const char	*srP_name;	/* name of parameter */
     void	(*srP_proc)();	/* Procedure processing this parameter */
 } srParms[] = {
     {"rate",		irSrSetRate},
@@ -1779,7 +1779,7 @@ irSearchCmd(w, cmd)
 	/* Lookup parameter name in contact parm table */
 	which = LookupStruct(
 	    cmd->tx_argv[2],
-	    (char **) srParms,
+	    (const LookupTable *) srParms,
 	    sizeof srParms[0]);
 
 	/* Process table lookup */
@@ -1863,9 +1863,9 @@ irSpacingsCmd(w, cmd)
     int which, value, argI, i, n;
 
     /* Special Value Table */
-    static struct
+    static const struct
     {
-	char	*sV_name;	/* name of value */
+	const char *sV_name;	/* name of value */
 	int     sV_value;	/* corresponding interger value */
     } sValue[] = {
 	{"n",		-1},
@@ -1876,9 +1876,9 @@ irSpacingsCmd(w, cmd)
     };
 
     /* Subcell Table */
-    static struct
+    static const struct
     {
-	char	*sT_name;	/* name of value */
+	const char *sT_name;	/* name of value */
 	int     sT_value;	/* corresponding interger value */
     } subcellTable[] = {
 	{"subcell",		TT_SUBCELL},
@@ -1976,7 +1976,7 @@ irSpacingsCmd(w, cmd)
 	    /* if not a real type, check to see if "SUBCELL" */
 	    which = LookupStruct(
 		cmd->tx_argv[3],
-		(char **) subcellTable,
+		(const LookupTable *) subcellTable,
 		sizeof subcellTable[0]);
 	    if ( which>= 0)
 	        tileType = TT_SUBCELL;
@@ -2033,7 +2033,7 @@ irSpacingsCmd(w, cmd)
 		/* if not a real type, check to see if "SUBCELL" */
 		which = LookupStruct(
 		    cmd->tx_argv[argI],
-		    (char **) subcellTable,
+		    (const LookupTable *) subcellTable,
 		    sizeof subcellTable[0]);
 		if ( which>= 0)
 	        tileType = TT_SUBCELL;
@@ -2066,7 +2066,7 @@ irSpacingsCmd(w, cmd)
 		/* Lookup in special value table */
 		which = LookupStruct(
 		    s,
-		    (char **) sValue,
+		    (const LookupTable *) sValue,
 		    sizeof sValue[0]);
 
 		/* Process result of lookup */
@@ -2233,9 +2233,9 @@ irVersionCmd(w, cmd)
  */
 
 /* Wizard Parameter Table */
-static struct
+static const struct
 {
-    char	*wzdP_name;	/* name of parameter */
+    const char	*wzdP_name;	/* name of parameter */
     void	(*wzdP_proc)();	/* Procedure processing this parameter */
 } wzdParms[] = {
     {"bloom",		irWzdSetBloomCost},
@@ -2276,7 +2276,7 @@ irWizardCmd(w, cmd)
 	/* Lookup parameter name in contact parm table */
 	which = LookupStruct(
 	    cmd->tx_argv[2],
-	    (char **) wzdParms,
+	    (const LookupTable *) wzdParms,
 	    sizeof wzdParms[0]);
 
 	/* Process table lookup */
@@ -2509,7 +2509,7 @@ irSaveParametersCmd(w, cmd)
 
 /*--- Subcommand Table ---*/
 
-SubCmdTableE irSubcommands[] = {
+const SubCmdTableE irSubcommands[] = {
     {"contacts",	irContactsCmd,
     "set route-contact parameters",
     "contacts [type] [parameter] [value1] ... [valuen]\n\
@@ -2637,7 +2637,7 @@ IRCommand(w, cmd)
 	/* Lookup subcommand in table */
 	which = LookupStruct(
 	    cmd->tx_argv[1],
-	    (char **) irSubcommands,
+	    (const LookupTable *) irSubcommands,
 	    sizeof irSubcommands[0]);
 
         /* Process result of lookup */
diff --git a/irouter/irTestCmd.c b/irouter/irTestCmd.c
index 59fa973f..efb0fbd4 100644
--- a/irouter/irTestCmd.c
+++ b/irouter/irTestCmd.c
@@ -52,12 +52,12 @@ static char rcsid[] __attribute__ ((unused)) = "$Header: /usr/cvsroot/magic-8.0/
 /* Subcommand table - declared here since its referenced before defined */
 typedef struct
 {
-    char	*sC_name;	/* name of iroute subcommand */
+    const char	*sC_name;	/* name of iroute subcommand */
     void	(*sC_proc)();	/* Procedure implementing this subcommand */
-    char 	*sC_commentString;
-    char	*sC_usage;
+    const char 	*sC_commentString;
+    const char	*sC_usage;
 } TestCmdTableE;
-extern TestCmdTableE irTestCommands[];
+extern const TestCmdTableE irTestCommands[];
 
 
 /*
@@ -154,7 +154,7 @@ irHelpTstCmd(w, cmd)
 	/* Lookup subcommand in table, and printed associated help info */
 	which = LookupStruct(
 	    cmd->tx_argv[2],
-	    (char **) irTestCommands,
+	    (const LookupTable *) irTestCommands,
 	    sizeof irTestCommands[0]);
 
         /* Process result of lookup */
@@ -219,7 +219,7 @@ irParmsTstCmd(w, cmd)
 }
 
 /*--------------------------- Command Table ------------------------------ */
-TestCmdTableE irTestCommands[] = {
+const TestCmdTableE irTestCommands[] = {
     {"debug",	irDebugTstCmd,
     "set or clear debug flags",
     "debug [flag] [value]"},
@@ -284,7 +284,7 @@ IRTest(w, cmd)
 	/* Lookup subcommand in table */
 	which = LookupStruct(
 	    cmd->tx_argv[1],
-	    (char **) irTestCommands,
+	    (const LookupTable *) irTestCommands,
 	    sizeof irTestCommands[0]);
 
         /* Process result of lookup */
diff --git a/mzrouter/mzTech.c b/mzrouter/mzTech.c
index d65d5651..250af032 100644
--- a/mzrouter/mzTech.c
+++ b/mzrouter/mzTech.c
@@ -812,7 +812,7 @@ mzTechSpacing(argc, argv)
     char *s;
 
     /* Subcell Table */
-    static struct
+    static const struct
     {
 	char	*sT_name;	/* name of value */
 	int     sT_value;	/* corresponding interger value */
@@ -849,7 +849,7 @@ mzTechSpacing(argc, argv)
 	    /* if not a real type, check to see if "SUBCELL" */
 	    which = LookupStruct(
 		argv[argI],
-		(LookupTable *) subcellTable,
+		(const LookupTable *) subcellTable,
 		sizeof subcellTable[0]);
 	    if ( which>= 0)
 	        tileType = TT_SUBCELL;
diff --git a/mzrouter/mzTestCmd.c b/mzrouter/mzTestCmd.c
index 526d291b..4273f5df 100644
--- a/mzrouter/mzTestCmd.c
+++ b/mzrouter/mzTestCmd.c
@@ -53,13 +53,13 @@ static char rcsid[] __attribute__ ((unused)) = "$Header: /usr/cvsroot/magic-8.0/
 /* Subcommand table - declared here since its referenced before defined */
 typedef struct
 {
-    char	*sC_name;	/* name of iroute subcommand */
+    const char	*sC_name;	/* name of iroute subcommand */
     void	(*sC_proc)();	/* Procedure implementing this
 				       subcommand */
-    char 	*sC_commentString;
-    char	*sC_usage;
+    const char 	*sC_commentString;
+    const char	*sC_usage;
 } TestCmdTableE;
-extern TestCmdTableE mzTestCommands[];
+extern const TestCmdTableE mzTestCommands[];
 
 
 /*
@@ -251,7 +251,7 @@ mzHelpTstCmd(w, cmd)
 	/* Lookup subcommand in table, and printed associated help info */
 	which = LookupStruct(
 	    cmd->tx_argv[2],
-	    (LookupTable *) mzTestCommands,
+	    (const LookupTable *) mzTestCommands,
 	    sizeof mzTestCommands[0]);
 
         /* Process result of lookup */
@@ -536,7 +536,7 @@ mzVersionCmd(w, cmd)
 
 /*--------------------------- Command Table ------------------------------ */
 
-TestCmdTableE mzTestCommands[] = {
+const TestCmdTableE mzTestCommands[] = {
     {"debug",	mzDebugTstCmd,
     "set or clear debug flags",
     "debug [flag] [value]"},
@@ -592,7 +592,7 @@ MZTest(w, cmd)
 	/* Lookup subcommand in table */
 	which = LookupStruct(
 	    cmd->tx_argv[1],
-	    (LookupTable *) mzTestCommands,
+	    (const LookupTable *) mzTestCommands,
 	    sizeof mzTestCommands[0]);
 
         /* Process result of lookup */
diff --git a/plot/plotVers.c b/plot/plotVers.c
index f5698e1d..7e7df395 100644
--- a/plot/plotVers.c
+++ b/plot/plotVers.c
@@ -407,7 +407,7 @@ PlotColorVersTechLine(sectionName, argc, argv)
     char *argv[];		/* Pointers to fields of line. */
 {
     VersatecStyle *new;
-    static struct { char *l_str; int l_color; } colors[] = {
+    static const struct { const char *l_str; int l_color; } colors[] = {
 	{"black",   BLACK},
 	{"cyan",    CYAN},
 	{"magenta", MAGENTA},
@@ -449,7 +449,7 @@ PlotColorVersTechLine(sectionName, argc, argv)
 	    freeMagic((char *)new);
 	    return TRUE;
 	}
-	i = LookupStruct(argv[1], (LookupTable *) colors, sizeof colors[0]);
+	i = LookupStruct(argv[1], (const LookupTable *) colors, sizeof colors[0]);
 	if (i < 0)
 	{
 	    TechError("First field must be BLACK, CYAN, MAGENTA or YELLOW.\n");
diff --git a/plow/PlowTech.c b/plow/PlowTech.c
index 7ebabe89..611ee225 100644
--- a/plow/PlowTech.c
+++ b/plow/PlowTech.c
@@ -175,9 +175,9 @@ PlowDRCLine(sectionName, argc, argv)
     char *argv[];
 {
     int which;
-    static struct
+    static const struct
     {
-	char	*rk_keyword;	/* Initial keyword */
+	const char *rk_keyword;	/* Initial keyword */
 	int	 rk_minargs;	/* Min # arguments */
 	int	 rk_maxargs;	/* Max # arguments */
 	int    (*rk_proc)();	/* Procedure implementing this keyword */
@@ -193,7 +193,7 @@ PlowDRCLine(sectionName, argc, argv)
      * Leave the job of printing error messages to the DRC tech file reader.
      * We only process a few of the various design-rule types here anyway.
      */
-    which = LookupStruct(argv[0], (LookupTable *) ruleKeys, sizeof ruleKeys[0]);
+    which = LookupStruct(argv[0], (const LookupTable *) ruleKeys, sizeof ruleKeys[0]);
     if (which >= 0)
     {
 	rp = &ruleKeys[which];
diff --git a/plow/PlowTest.c b/plow/PlowTest.c
index 48e5a65a..aaae633b 100644
--- a/plow/PlowTest.c
+++ b/plow/PlowTest.c
@@ -99,11 +99,11 @@ typedef enum
     PC_WHENTOP, PC_WHENBOT,
     PC_SETD, PC_CLRD, PC_SHOWD
 } pCmd;
-struct
+const struct
 {
-    char *p_name;
+    const char *p_name;
     pCmd  p_cmd;
-    char *p_help;
+    const char *p_help;
 } plowCmds[] = {
     {"clrdebug",	PC_CLRD,	"flags"},
     {"help",		PC_HELP,	""},
@@ -423,7 +423,7 @@ plowGetCommand(cmd)
     }
 
     plowIndex = LookupStruct(cmd->tx_argv[1],
-			(LookupTable *) plowCmds, sizeof plowCmds[0]);
+			(const LookupTable *) plowCmds, sizeof plowCmds[0]);
     if (plowIndex < 0)
     {
 	TxError("Bad plowing command '%s'.\n", cmd->tx_argv[1]);
diff --git a/router/rtrCmd.c b/router/rtrCmd.c
index 590245d9..7eeb0a6d 100644
--- a/router/rtrCmd.c
+++ b/router/rtrCmd.c
@@ -267,9 +267,9 @@ CmdGaRoute(w, cmd)
     int n, chanType;
     Rect editArea;
     FILE *f;
-    static struct
+    static const struct
     {
-	char	*cmd_name;
+	const char *cmd_name;
 	cmdType	 cmd_val;
     } cmds[] = {
 	{"channel xl yl xh yh [type]\n\
@@ -290,7 +290,7 @@ channel	[type]		define a channel",			CHANNEL},
     if (cmd->tx_argc == 1)
 	goto doRoute;
 
-    n = LookupStruct(cmd->tx_argv[1], (LookupTable *) cmds, sizeof cmds[0]);
+    n = LookupStruct(cmd->tx_argv[1], (const LookupTable *) cmds, sizeof cmds[0]);
     if (n < 0)
     {
 	if (n == -1)
diff --git a/utils/geometry.c b/utils/geometry.c
index 7d751e33..b5b06503 100644
--- a/utils/geometry.c
+++ b/utils/geometry.c
@@ -360,9 +360,9 @@ GeoNameToPos(name, manhattan, verbose)
 			 * valid directions.
 			 */
 {
-    static struct pos
+    static const struct pos
     {
-	char	*pos_name;
+	const char *pos_name;
 	int	 pos_value;
 	bool	 pos_manhattan;
     }
@@ -403,11 +403,11 @@ GeoNameToPos(name, manhattan, verbose)
 	{"west",	GEO_WEST,		TRUE},
 	{0}
     };
-    struct pos *pp;
     char *fmt;
+    const struct pos *pp;
     int pos;
 
-    pos = LookupStruct(name, (LookupTable *) positions, sizeof positions[0]);
+    pos = LookupStruct(name, (const LookupTable *) positions, sizeof positions[0]);
 
     if ((pos >= 0) && (!manhattan || positions[pos].pos_manhattan))
 	return positions[pos].pos_value;
diff --git a/utils/set.c b/utils/set.c
index 8c0637bd..cc63c237 100644
--- a/utils/set.c
+++ b/utils/set.c
@@ -104,9 +104,9 @@ SetNoisyBool(parm,valueS,file)
     int n, which, result = -2;
 
     /* Bool string Table */
-    static struct
+    static const struct
     {
-	char	*bS_name;	/* name */
+	const char *bS_name;	/* name */
 	bool    bS_value;	/* procedure processing this parameter */
     } boolStrings[] = {
 	{"yes",		TRUE},
@@ -126,7 +126,7 @@ SetNoisyBool(parm,valueS,file)
 	/* Lookup value string in boolString table */
 	which = LookupStruct(
 	    valueS,
-	    (LookupTable *) boolStrings,
+	    (const LookupTable *) boolStrings,
 	    sizeof boolStrings[0]);
 
         /* Process result of lookup */