diff --git a/include/libbb.h b/include/libbb.h
index daa96728b..d2563999a 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -1828,7 +1828,12 @@ struct smaprec {
 	unsigned long stack;
 	unsigned long smap_pss, smap_swap;
 	unsigned long smap_size;
-	unsigned long smap_start;
+	// For mixed 32/64 userspace, 32-bit pmap still needs
+	// 64-bit field here to correctly show 64-bit processes:
+	unsigned long long smap_start;
+	// (strictly speaking, other fields need to be wider too,
+	// but they are in kbytes, not bytes, and they hold sizes,
+	// not start addresses, sizes tend to be less than 4 terabytes)
 	char smap_mode[5];
 	char *smap_name;
 };
diff --git a/libbb/procps.c b/libbb/procps.c
index 9d8a921df..af3ad86ff 100644
--- a/libbb/procps.c
+++ b/libbb/procps.c
@@ -120,11 +120,11 @@ void FAST_FUNC free_procps_scan(procps_status_t* sp)
 }
 
 #if ENABLE_FEATURE_TOPMEM || ENABLE_PMAP
-static unsigned long fast_strtoul_16(char **endptr)
+static unsigned long long fast_strtoull_16(char **endptr)
 {
 	unsigned char c;
 	char *str = *endptr;
-	unsigned long n = 0;
+	unsigned long long n = 0;
 
 	/* Need to stop on both ' ' and '\n' */
 	while ((c = *str++) > ' ') {
@@ -238,8 +238,8 @@ int FAST_FUNC procps_read_smaps(pid_t pid, struct smaprec *total,
 
 			*tp = ' ';
 			tp = buf;
-			currec.smap_start = fast_strtoul_16(&tp);
-			currec.smap_size = (fast_strtoul_16(&tp) - currec.smap_start) >> 10;
+			currec.smap_start = fast_strtoull_16(&tp);
+			currec.smap_size = (fast_strtoull_16(&tp) - currec.smap_start) >> 10;
 
 			strncpy(currec.smap_mode, tp, sizeof(currec.smap_mode)-1);
 
diff --git a/procps/pmap.c b/procps/pmap.c
index c8fa0d280..9e541c707 100644
--- a/procps/pmap.c
+++ b/procps/pmap.c
@@ -37,6 +37,12 @@
 # define DASHES "--------"
 #endif
 
+#if ULLONG_MAX == 0xffffffff
+# define AFMTLL "8"
+#else
+# define AFMTLL "16"
+#endif
+
 enum {
 	OPT_x = 1 << 0,
 	OPT_q = 1 << 1,
@@ -46,7 +52,7 @@ static void print_smaprec(struct smaprec *currec, void *data)
 {
 	unsigned opt = (uintptr_t)data;
 
-	printf("%0" AFMT "lx ", currec->smap_start);
+	printf("%0" AFMTLL "llx ", currec->smap_start);
 
 	if (opt & OPT_x)
 		printf("%7lu %7lu %7lu %7lu ",