diff --git a/sources/declare.h b/sources/declare.h
index 802e171e..47e5315c 100644
--- a/sources/declare.h
+++ b/sources/declare.h
@@ -68,12 +68,18 @@
           ParseNumber(x,s) if ( sgn ) x = -x; }
 
 /* (n) is necessary here, since the macro is sometimes passed dereferenced pointers for n */
-#define NCOPY(s,t,n) { while ( (n)-- > 0 ) { *s++ = *t++; } }
-/*#define NCOPY(s,t,n) { memcpy(s,t,n*sizeof(WORD)); s+=n; t+=n; n = -1; }*/
+/*#define NCOPY(s,t,n) { while ( (n)-- > 0 ) { *s++ = *t++; } }
 #define NCOPYI(s,t,n) { while ( (n)-- > 0 ) { *s++ = *t++; } }
 #define NCOPYB(s,t,n) { while ( (n)-- > 0 ) { *s++ = *t++; } }
 #define NCOPYI32(s,t,n) { while ( (n)-- > 0 ) { *s++ = *t++; } }
-#define WCOPY(s,t,n) { int nn=n; WORD *ss=(WORD *)s, *tt=(WORD *)t; while ( (nn)-- > 0 ) { *ss++ = *tt++; } }
+#define WCOPY(s,t,n) { int nn=n; WORD *ss=(WORD *)s, *tt=(WORD *)t; while ( (nn)-- > 0 ) { *ss++ = *tt++; } }*/
+
+/* Use memmove: we can't guarantee that s and t do not overlap in uses of the macros */
+#define NCOPY(s,t,n) { memmove(s,t,(n)*sizeof(*s)); s+=n; t+=n; n=0; }
+#define NCOPYI(s,t,n) { NCOPY(s,t,n); }
+#define NCOPYB(s,t,n) { NCOPY(s,t,n); }
+#define NCOPYI32(s,t,n) { NCOPY(s,t,n); }
+#define WCOPY(s,t,n) { int nn=n; WORD *ss=(WORD *)s, *tt=(WORD *)t; NCOPY(ss,tt,nn); }
 
 #define NeedNumber(x,s,err) { int sgn = 1;                               \
 		while ( *s == ' ' || *s == '\t' || *s == '-' || *s == '+' ) {      \
diff --git a/sources/execute.c b/sources/execute.c
index 2514370c..6279cb91 100644
--- a/sources/execute.c
+++ b/sources/execute.c
@@ -1601,7 +1601,9 @@ NextSymbol2:;
 	if ( AR.BracketOn < 0 ) {
 		s1 = t1; t1 = t2; t2 = s1;
 	}
-	do { *t2++ = *t++; } while ( t < (WORD *)tStopa );
+	/* Old code copied 1 element if copy == 0. This doesn't happen in the test suite. */
+	LONG copy = tStopa - t;
+	NCOPY(t2, t, copy);
 	t = AT.WorkPointer;
 	i = WORDDIF(t1,term1);
 	*t++ = 4 + i + WORDDIF(t2,term2);
diff --git a/sources/if.c b/sources/if.c
index 0e0f2485..3490da24 100644
--- a/sources/if.c
+++ b/sources/if.c
@@ -816,7 +816,7 @@ donemul:		if ( i ) { ncoef2 = 1; coef2 = Spac2; coef2[0] = coef2[1] = 1; }
 		}
 		coef1 = Spac1;
 		i = 2*ABS(ncoef2);
-		for ( j = 0; j < i; j++ ) coef1[j] = coef2[j];
+		WCOPY(coef1, coef2, i);
 		ncoef1 = ncoef2;
 SkipCond:
 		ifp += ifp[1];
diff --git a/sources/proces.c b/sources/proces.c
index 93ac5c80..45683d53 100644
--- a/sources/proces.c
+++ b/sources/proces.c
@@ -2174,7 +2174,8 @@ int InFunction(PHEAD WORD *term, WORD *termout)
 		if ( AR.TePos ) {
 			if ( ( term + AR.TePos ) == t ) {
 				m = termout;
-				while ( from < t ) *m++ = *from++;
+				LONG copy = t - from;
+				NCOPY(m, from, copy);
 				*m++ = DENOMINATOR;
 				*m++ = t[1] + 4 + FUNHEAD + ARGHEAD;
 				*m++ = DIRTYFLAG;
@@ -2185,7 +2186,8 @@ int InFunction(PHEAD WORD *term, WORD *termout)
 				*m++ = t[1] + 4;
 				t[3] = -t[3];
 				v = t + t[1];
-				while ( t < v ) *m++ = *t++;
+				copy = v - t;
+				NCOPY(m, t, copy);
 				from[3] = -from[3];
 				*m++ = 1;
 				*m++ = 1;
@@ -2220,11 +2222,10 @@ int InFunction(PHEAD WORD *term, WORD *termout)
 					AR.DeferFlag = 0;
 					v = t + *t;
 					t += ARGHEAD;		/* First term */
-					w = 0;	/* to appease the compilers warning devices */
-					while ( from < t ) {
-						if ( from == u ) w = m;
-						*m++ = *from++;
-					}
+					LONG copy = t - from;
+					const LONG size = t - u;
+					NCOPY(m, from, copy);
+					w = m - size;
 					to = m;
 					NewSort(BHEAD0);
 					if ( *u == AR.PolyFun && AR.PolyFunType == 2 ) {
@@ -2314,11 +2315,10 @@ int InFunction(PHEAD WORD *term, WORD *termout)
 						&& ( *u != AR.PolyFun ) ) { AN.ncmod = 0; }
 					AR.DeferFlag = 0;
 					v = t + 2;
-					w = 0;	/* to appease the compilers warning devices */
-					while ( from < t ) {
-						if ( from == u ) w = m;
-						*m++ = *from++;
-					}
+					LONG copy = t - from;
+					const LONG size = t - u;
+					NCOPY(m, from, copy);
+					w = m - size;
 					to = m;
 					switch ( d->type ) {
 						case DOLINDEX:
@@ -2481,11 +2481,10 @@ int InFunction(PHEAD WORD *term, WORD *termout)
 					u points at the start of the function
 					t points at the start of the argument
 */
-					w = 0;
-					while ( from < t ) {
-						if ( from == u ) w = m;
-						*m++ = *from++;
-					}
+					LONG copy = t - from;
+					const LONG size = t - u;
+					NCOPY(m, from, copy);
+					w = m - size;
 					if ( ( numterms & MAXPOSITIVE ) == numterms ) {
 						*m++ = -SNUMBER; *m++ =  numterms & MAXPOSITIVE;
 						w[1] += 1;
@@ -2505,7 +2504,8 @@ int InFunction(PHEAD WORD *term, WORD *termout)
 					}
 					from++;  /* Skip our function */
 					r = term + *term;
-					while ( from < r ) *m++ = *from++;
+					copy = r - from;
+					NCOPY(m, from, copy);
 					if ( (m-termout) > (LONG)(AM.MaxTer/sizeof(WORD)) ) {
 						MLOCK(ErrorMessageLock);
 						MesPrint("Output term too large (%d words) (MaxTermSize: %d words)", m-termout, AM.MaxTer/sizeof(WORD));
@@ -2548,11 +2548,11 @@ int InFunction(PHEAD WORD *term, WORD *termout)
 					if ( ( AN.ncmod != 0 )
 						&& ( ( AC.modmode & ALSOFUNARGS ) == 0 )
 						&& ( *u != AR.PolyFun ) ) { AN.ncmod = 0; }
-					m = termout; w = 0;
-					while ( from < t ) {
-						if ( from == u ) w = m;
-						*m++ = *from++;
-					}
+					m = termout;
+					LONG copy = t - from;
+					const LONG size = t - u;
+					NCOPY(m, from, copy);
+					w = m - size;
 					to = m;
 					switch ( d->type ) {
 						case DOLINDEX:
@@ -2650,7 +2650,8 @@ wrongtype:;
 					w[1] = w[1] - 2 + (m-to);
 					from += 2;
 					term += *term;
-					while ( from < term ) *m++ = *from++;
+					copy = term - from;
+					NCOPY(m, from, copy);
 					if ( sign < 0 ) m[-1] = -m[-1];
 					if ( (m-termout) > (LONG)(AM.MaxTer/sizeof(WORD)) ) {
 						MLOCK(ErrorMessageLock);
@@ -3413,10 +3414,10 @@ SkipCount:	level++;
 						are involved in a match(). Hence we have to make
 						a private copy here!!!!
 */
-						WORD ic, jc, *ifcode, *jfcode;
+						WORD jc, *ifcode, *jfcode;
 						jfcode = C->lhs[level]; jc = jfcode[1];
 						ifcode = AT.WorkPointer; AT.WorkPointer += jc;
-						for ( ic = 0; ic < jc; ic++ ) ifcode[ic] = jfcode[ic];
+						WCOPY(ifcode, jfcode, jc);
 						while ( !DoIfStatement(BHEAD ifcode,term) ) {
 							level = C->lhs[level][2];
 							if ( C->lhs[level][0] != TYPEELIF ) break;
@@ -5253,11 +5254,14 @@ int PrepPoly(PHEAD WORD *term,WORD par)
 */
 		m = term + *term;
 		if ( poly + poly[1] < tstop ) {
-			for ( i = 0; i < poly[1]; i++ ) m[i] = poly[i];
+			LONG copy = poly[1];
+			WCOPY(m, poly, copy);
 			t = poly; v = poly + poly[1];
-			while ( v < tstop ) *t++ = *v++;
+			copy = tstop - v;
+			NCOPY(t, v, copy);
 			poly = t;
-			for ( i = 0; i < m[1]; i++ ) t[i] = m[i];
+			copy = m[1];
+			WCOPY(t, m, copy);
 			t += m[1];
 		}
 		AT.PolyAct = WORDDIF(poly,term);
diff --git a/sources/sort.c b/sources/sort.c
index 1005e17c..c93e2aa1 100644
--- a/sources/sort.c
+++ b/sources/sort.c
@@ -4624,9 +4624,7 @@ int StoreTerm(PHEAD WORD *term)
 			while ( ( t = *ss++ ) != 0 ) {
 				j = *t;
 				if ( j < 0 ) j = t[1] + 2;
-				while ( --j >= 0 ){
-				  *lfill++ = *t++;
-				}
+				NCOPY(lfill, t, j);
 			}
 		}
 		*lfill++ = 0;
@@ -4636,7 +4634,7 @@ int StoreTerm(PHEAD WORD *term)
 		*(S->PoinFill) = S->sFill = S->sBuffer;
 	}
 	j = *term;
-	while ( --j >= 0 ) *S->sFill++ = *term++;
+	NCOPY(S->sFill, term, j);
 	S->sTerms++;
 	S->GenTerms++;
 	S->TermsLeft++;
diff --git a/sources/threads.c b/sources/threads.c
index 9176e4c6..0a311a09 100644
--- a/sources/threads.c
+++ b/sources/threads.c
@@ -3543,9 +3543,9 @@ int PutToMaster(PHEAD WORD *term)
 	fill = AT.SB.MasterFill[i];     /* Where we are filling */
 	top = AT.SB.MasterStop[i];      /* End of the block */
 	while ( j > 0 ) {
-		while ( j > 0 && fill < top ) {
-			*fill++ = *t++; j--;
-		}
+		LONG copy = MiN(top - fill, j);
+		j -= copy;
+		NCOPY(fill, t, copy);
 		if ( j > 0 ) {
 /*
 			We reached the end of the block.